You need only wdrt drivers. Have you tried 830 efiesp.bin?
I tried a system restore to before I installed the qualcom drivers (I think, not sure), still no good. Phone still can't be recognized by the laptop.
Phone just enters the "can't find bootable option" loop and nothing else happens.
Now I must be really screwed.
Edit:
GOD DAMNIT AGAIN!
Used a different PC, phone went into flash mode, simply removed it, reconnected it to my PC, opened up WPI and tried to flash the EFIESP.bin partition from that .zip on the link you sent. WPI simply crashed. It just quits, no error message. I then tried to unlock bootloader in those partitions to see if it would do something, but it said it couldn't be unlocked.
I don't know. What are the small steps I could be missing?
I still think editing an .ffu to change the registry values would be the better option. But I'm not familiar with that is mentioned in this forum post, hence me asking for help. I need to first find out where the registry values are stored and how to change them. I think I need to mount the .ffu first (easy), find the registry trees (don't know which ones) and edit them (don't know how to edit external registry files).