Ok, I'll try not to lose anyone through this.
I have a friend who had 2 xboxes and he wanted me to soft mod one and fix the other.
One was fine (Xbox A) and one had a shitty paint job and was screwed (Xbox

.
I had a softmodded Box (Xbox 69)
so i went to soft mod XBA and screwed up a hotswap by not locking the HDD before reconecting the IDE cable.
He told me he ran a test on the motherboard of XBB with his tester and found that the Heat Synch for the GPU was fucked so he replaced it (he knows nothing about xbox, just PC's) It still didn't work so i decided to take on the task of fixing it (still XBB). I noticed that the HDD was making a clicking noise so i opened it and found that the arm wasn't staying put. It would just bounce around everywhere! So I decide i needed to replace the HDD. I opened up another Western Digital HDD and swaped out the discs in them to get the eeprom from XBB. The other HDD was from XB69. It didn't work. I kept getting an error message with no code. So i said "screw it" and threw them back in thier correct HDD cases and tested the HDD for XB69 before i put the cover of the drive back on. I had the screw in the top of the arm to hold it down and everything, just no cover. It worked fine. So i put the cover back on the HDD of XB69 and put it back in my xbox. When i went to boot i got error 9. I have been tweaking the screw on the arm for an hour or so now, I've tried cover on and off. It won't work. I always get either error 7 or 9. I have a new chip in the mail to fix XBA, Hopefully someone knows how to fix this so i dont have to pay $35 for another.
Thank you for even trying to figure this out. I'm sure I probably left holes in this. Tell me if you need me to elaborate.