[Windows Phone 8 Development and Hacking] rustybob:
Thank you for the fantastic app. Long story short, I bought a Lumia 920 off Craigslist for $40 with a wireless charger. The ad said Glance wasn't working, so I suspected that it was just dirty under the screen by the proximity sensor, which would be an easy fix, and then I could flip the phone for more money. That wasn't the problem, but I still think I got my money's worth out of the deal. The charger is nice to have, and I made a post in the Lumia 920 forum as well. This was the AT&T version of the phone, and while it shared the same part number as the Canadian Rogers version, it did not support AWS HSPA. Nobody ever replied, but I believe I solved the mystery of why it didn't work. I noticed some antenna pins pushed down that weren't on a Rogers version that I had to replace the glass. I lifted them up, booted up the phone, and it immediately connected to the Mobilicity network. Calling and data worked, and the signal was just as strong as my Rogers version of the phone.

Anyways, the problem with the phone ran much deeper than dirt by the proximity sensor. The previous owner had flashed the Rogers version of the firmware on the phone. I suspected the issue was firmware related, but there was no way to flash back to the AT&T version until now. Using the Nokia Care Suite, I put the phone in test mode, and it failed multiple tests, the accelerometer, proximity sensor, front camera, microphone, and a few others. I know that the brightness settings on the phone also couldn't be changed. All of them said the error was due to a missing driver.

WPInternals finally allowed me to flash the original AT&T firmware for this phone. The Windows Device Recovery Tool now works without issue. The AT&T firmware has fixed some things. Auto brightness still doesn't work, but it's not stuck on low, it can go in between the three brightness levels. In Test Mode, it fails five tests still, with the accelerometer, proximity sensor, front camera, and microphone still the big issues. Previously, Glance couldn't be installed, but it does install fine now, it just doesn't work because of the proximity sensor. Trying to update to Windows 10 previously resulted in a soft brick, but works fine now.

Because of the issues on this phone, it's been the perfect candidate to play around with on WPInternals. I think it would be awesome to get it back into fully working condition again, though. Some internet searching hasn't brought up much info about this. One person had the issue disappear after the 8.1 update was pushed to their phone. Another did a hard reset with the SIM inserted. Neither of these worked.

Maybe I'm wrong, but I do have the suspicion that the issues are, in fact, driver related. The camera app worked fine when I bought it, but after doing a reset from the About screen, the camera app never launched again. I suspect that there would be no way to change the drivers through Mass Storage mode on a running phone, since those files should hypothetically be in use. So I'm thinking that making a custom ROM to flash might fix the issue. Would anyone happen to know where in the file system the driver files would be located? I could extract them from a different RM-820 (or perhaps an RM-821) ROM, and see if it worked. I don't care if I fully bricked the phone by doing this, since it's not really a useable phone at the moment, and the charger and the knowledge learned have been worth the $40 I paid already. The fact that some functionality was restored by going back to the original AT&T software, and that Windows 10 is now installable, also gives me some hope that this is a software-related issue.

Also, I just noticed the Build and Capture section in the Getting Started section. It mentions that registry settings survive a hard reset. I think I will attempt a build and capture, and use SDELETE to clean up the image.

It doesn't seem like this is a very common issue. Or, perhaps, people have just assumed that the issue isn't fixable. If it can be fixed through software, I'd love to give that information back to this community. The info on XDA has saved me many times, it would be nice to give something back.