(Yes, it does rime, if you pronounce the acronym the french way :D)

TL; DR: Don't try to create a bootable USB for Windows by fiddling around with diskpart. Get a USB disk drive instead, or use proper tools. If your Windows boot breaks, have a DVD on hand, go to repair mode and run the automated repair up to three times. If it says "not compatible", try running the DVD as UEFI from your BIOS. Have up-to-date backups and a Linux live USB on hand at all times. And dual-boot is apparently easier than the Internet seems to think.

Let's start with a quick timeline of the events of late last week:

• Received the last parts for my desktop computer after a post hiccup.
• Put the Beast together. It's surprisingly easy nowadays! Just don't forget to plug in the CPU fan. Just sayin'.
• Find out that Windows 8.1 was 300SEK cheaper as an OEM disk from Webhallen.
• Decide that surely it won't be that hard to create a bootable USB from that.

WRONG. It turns out that the OEM disk does not allow you to "Install to media" from the Windows 8 setup, like a retail version does. Unfortunately the tutorial I found suggested doing some blood magic with diskpart. I created an ISO, followed the commands, thinking I was doing things right. But some process was holding a handle on a file from the ISO (?), so I just went into ProcessExplorer, closed the handle and kept going. Yes, this should have set off a few alarm bells. I was still getting "File in use" errors, so I restarted...

Well, this is interesting.

Yes, you got this right, I managed to fry my laptop's boot by trying to make the USB to install my desktop. "Restart and select proper Boot device". That didn't sound very good. Was this "BCD" thing important, then...?

Cutting to the chase, of course it was. BCD stands for "Boot Configuration Data", and it's a vital file if you want your Windows to start at all. I sighed, dug up the Linux Mint USB stick I had already made, fired up my Macbook Air for some googling, and settled in for a very annoying Sunday afternoon. Apologies to my twitter followers for all the cursing, by the way :)

First step was getting it to boot again on Mint, to make sure everything was alright apart from the boot itself. I had made the USB previously for the desktop. This was completely painless: download the ISO from the website (I went for Cinnamon), use a tool to create a bootable USB (I used Universal USB Installer), and there you go. You might have to iterate on the formatting somewhat (NTFS or FAT32). Then start up the computer, enter the BIOS, and set the USB as the first boot device. I had to switch between the UEFI and the non-UEFI version to get it to start, wondering what that new acronym meant.

I got it to start up under Mint, checked my drives: relief, everything was still there. Note: at that point I kept trying to fix things without backing up first. This is a terrible idea and you should not do the same, I was lucky to not lose anything. Make a backup before you fiddle with your partition table! Also, everything that follows is made much more interesting by the fact I did not have a Windows 7 DVD handy.

Looking into GParted was quite educational: I saw that my laptop in fact has five partitions. "System", hidden (no letter assigned) and quite small. Another partition that GParted couldn't identify. Then "OS", my C: drive. "Data", my D: drive. And "Recovery", hidden as well. It was the first time I saw the naming schemes for those: sda for the hard drive, sda1 to sda5 for the paritions, sdb for the USB drive I had plugged in.

First thing I had vague memories of was the MBR (Master Boot Record). I couldn't explain to you exactly what it is, and frankly I didn't want to dig too deep. But basically the first possible reason for your Windows not to boot is that the installation is not listed in the MBR anymore. The easy way to fix this is by plopping in your Windows recovery disk, but as mentioned I didn't have one, so I tried doing things the hard way. Googling found this tutorial, which I followed religiously, with a ridiculous number of reboots in the process. It didn't help though. Since my Windows was still listed in the available boot devices, just failing to start, I started to suspect it was more serious than a broken MBR.

I then found out about BootRepair (thanks to Jeroen Baert for the tip). It's a Ubuntu tool but since Mint is a Ubuntu derivative, it's also available there. You have to add a new APT repository to get it, just follow the instructions on the page. Then you click the big friendly button, let it work its magic...

... Still no luck. Next step was Super GRUB Disk. I created a bootable USB from that, picked the right boot device, and was able to start it up. This USB I created from my Mac, using Mac Linux USB Loader. I think I had to format the USB to FAT32 beforehand from Disk Utilities. Once SGD starts it will list the available boots on your machine more extensively than your BIOS. There I saw the three Windows boots available: System, OS, Recovery. I tried to start each of them and got the same error message each time: it was failing to find the BCD file. The message went something like this:

File: /Boot/BCD
Status: 0xc000000f
Info: an error occurred while attempting to read the boot configuration data.

Throughout the previous googling, I had encountered "BCD" and "UEFI" more and more often. I looked into it a bit more and figured out that my laptop was a complicated case because of UEFI. I do not know the details (and don't want to know them), but it's some kind of more modern BIOS replacement which, for Windows, is coupled with some secure boot mechanism. It's the reason for the four-partition setup... and it makes fixing anything more complicated. I did not investigate the exact details, but apparently with BIOS you just have a blob at the very start of the disk that then points directly to the boot files. With UEFI you have this intermediary System partition making everything messier.

At this point it was becoming obvious that I needed a Windows recovery up and running if I was to get anywhere. I hunted down a Windows 7 ISO (which is completely legal to download), and created yet another bootable USB. I managed to boot from the USB after randomly toggling between UEFI and non-UEFI... somehow UEFI wasn't always the right one! "Repair my system", and it complained that the Windows I was trying to repair wasn't compatible. Darn.

This, however, does not prevent you from opening a command prompt. Hit Shift-F10 to get one. From there, I followed this tutorial. Solution one was a no-go due to the compatibility failure. Solution two did not work. Solution three, "Nuclear Holocaust", started throwing "The requested system device cannot be found" errors at me halfway through. Googling some more, it seems that the procedure will not behave properly unless you're running from a DVD. I cursed some more (sorry again, Twitter), turned the whole thing off for the night and used my Mac instead.

Luckily, I work for a tech company and not everybody's on vacation, so I was pretty optimistic about my odds of finding a Win7 DVD from a colleague. Daniel Collin came through with flying colors, along with a USB DVD reader that was going to allow me to setup my desktop. After finally completing a backup (don't wait like I did! Do it from the start!), I plopped in the disk on Tuesday and attempted to repair my system.

"Incompatible" again. Damn. I restarted, went back to the BIOS, and made sure to start the DVD as UEFI. And this time I was finally able to access the recovery mode! I ran the automated repair, let it run, restarted, booted up recovery again, ran the repair a second time, restarted... It's actually recommended to run it three times, but the third time couldn't find any issues anymore. So I rebooted, tweaked the devices order in the BIOS...

I was never so happy to see the Windows start screen.

Conclusion: This is a bit of an underwhelming finish, because it was automated repair magic that fixed it and not anything I was doing myself. My guess is that it was able to do what I tried to do with bcdedit but could not because of the error.

Bonus: Win8 + Mint dual boot on the desktop!

Since I wasn't done having fun with partitions, MBRs and other things which make me praise the sky I'm a software engineer and not a sysadmin, I wanted to fix up a dual boot on my brand new desktop. I used the USB disk drive to install Windows 8, which went swimmingly if you ignore the creepy default settings. I then picked up my faithful Mint live USB again, plopped it in, installed, rebooted... Nothing but Windows. Seems that by default it does not install in a way that makes you boot to GRUB. I found this wonderfully objective tutorial which explained a thing or two, and decided I was just going to be lazy and run BootRepair. I booted the live USB again, installed the package and ran it. The only problem I had while running the commands it suggested was a missing dependency (linux-headers-something): I just took the apt-get line that was failing, changed the package name to the missing dependency, ran that, then the original command, and it proceeded just fine. The final window said there were errors, but still advised rebooting, and so I did. I was greeted by GRUB asking me to pick an OS to boot, and everything seems to work fine. So, yay for BootRepair, and thanks to UEFI for forcing me to use magic tools instead of understanding what's happening.

Do note I did not have to disable SecureBoot at any point. Your mileage may vary, but it seems it's not necessary anymore and many tutorials on the web are out of date.

Second bonus: As a reward for making it through the whole post, here's a chocolate cake recipe I promised to write up.

Ingredients: 200g of dark baking chocolate, 100g of butter (preferably with salt in it), 50g of flour, 100g of sugar, three whole eggs (well, without the shell). Do not use milk chocolate or it will be too liquid.

Heat up oven at 220°C. Melt the chocolate and the butter together in a bain-marie, mixing slowly so that it gets a nice silky texture. While it's melting, prepare the flour, sugar and eggs in a mixing bowl, without mixing just yet. Add the chocolate and butter and mix quickly (or your eggs will turn to omelette from the heat...) until the whole thing is homogenous. Pour in a metal or Pyrex-like mold (one of them oval glass things for chicken is perfect): it should "feel" homogenous, neither too liquid not too solid, and make nice ribbons while you pour it. Then put in the oven for 10 minutes. It's perfect when you can stab it with a knife and have said knife come back with just a little chocolate on it. Leftovers can be stuck in the fridge for a very buttery texture that's awfully heavy but delicious too, though of course it's better warm.