Originally Posted by plotgee
When I first turn on it'll stay stuck in HTC white screen logo till battery dies.
If I hold volume rocker and power button to try to factory reset it'll try to initiate but then show and a phone logo with red exclamation mark.
I am almost positive i can restore this phone to working order because i remember a while back i put a galaxy s3 into similar condition and restored it using a program.. Ive been out of this stuff for a while so i forgot how i did it with the s3.
I WAS GIVEN THIS HTC AND IT WAS LIKE THIS WHEN I GOT IT.
Don't worry, this problem has cropped up before, and you're right, it is fixable. This is most commonly attributed to some weirdness with the boot.img flashed to your phone. Firstly, do you have a Vivid, Velocity, or Raider? And what provider does it use (e.g. AT&T)?
The first thing you'll want to try and do is pop out the battery, put it back in, then hold "volume down" and "power" until you get to the bootloader (it sounds like you've already gotten there):
You'll notice in the top portion, mine says "unlocked". Yours may say this, but may also say "locked" or "re-locked".
First thing's first; you'll want to download FASTBOOT (http://www.mediafire.com/download/9y...x/Fastboot.zip
and the HTC drivers (this is what I had in my flashing folder, so I upped it to mega: https://mega.co.nz/#!CV5RxY7L!Z_VNph...WRbvH2UKsCXCi0
just run the htc drivers and follow directions, nothing too major. Extract the contents of "fastboot.zip" to somewhere that's easy to access and remember (such as c:\FASTBOOT).
We're not going to do anything yet, this is just preparation.
If your bootloader is "locked" or "re-locked", then you can try restoring the original firmware with RUU. You'll want to read this thread first though:
Always need to be careful.
If you are "unlocked", then you need to boot your phone into the bootloader, select "fastboot" (by pressing power when "fastboot" is highlighted), and connect the phone to your computer via a data usb cable. Then, open a command prompt window, and type in: "<c:\FASTBOOT\fastboot.exe> oem lock", where <c:\FASTBOOT\fastboot.exe> is replaced with the location of your fastboot.exe.
I would recommend flashing the recovery image located in the thread I linked to just before (follow instructions provided), and only THEN applying an RUU update. Which RUU you apply is dependent on which device you have.
If anything is unclear, or you have any questions, PLEASE ask in reply to this post; it's better to go slowly and be sure of what you're doing.
I noticed you said you had previously owned an S3 and managed to fix the problem with that; if you are pretty familiar with flashing roms, you can also try to flash a custom ROM and see if that fixes your problem (guides should be on Vivid General or Q&A).