[XDA Assist] anvoice:
Hello,

Pretty new to rooting, tried to root my HTC Vivid to install some apps which are "incompatible" with my device. Unlocked bootloader and rooted successfully by installing TWRP recovery and installing the supersu zip. After copying the build.prop file to another folder I proceeded to make some minor changes to the build.prop file with ES File Explorer. Essentially changing the model ID of the phone to another device to try to prompt Google Play to show the incompoatible apps, didn't touch anything boot-related or anything else. Phone was working fine at that point, rebooting ok, but Google Play still showed the apps as incompatible, so I temporarily brought back the old build.prop file by copy/pasting it from the folder I made. The system indicated the copy was made successfully, and I tried to reboot once more. That is where the problem started.

When the power button is pressed for a second or so, the phone vibrates once and shows the starting splash screen (HTC) as it did when working, and then the screen goes blank, although the LED backlight is still on (so phone has power). Nothing comes after, no "HTC quietly brilliant" logo nor the chime that indicates it's booting up. At that point it stops responding to any stimulus except the removal of the battery, at which point the LED backlight finally goes off. Waiting for ~10min solved nothing, still blank black screen with backlight on. Upon reinserting the battery, the phone once again responds to the power button, with the same results.

I can boot to recovery by holding down Vol down and pressing power, and there I get the usual options including Fastboot, Recovery, etc. I tried doing a factory reset. It gives a bunch of error messages along the lines of "can't mount emmc", then says it's starting the reset, and gives a successful completion prompt after half a minute or so. However, that seems to do nothing at all to fix the problem (tried 4x times, with SD card in and out).

The only change that comes to mind is the last replacement of the build.prop file I did, which should have just restored the original. Assuming the factory reset doesn't actually reset that file (where would it get a copy to do so?) perhaps it being broken is preventing me from booting after the reset. Just my theory though, and could be something else.

From what I understand I could try putting a recovery image on the micro sd from a PC, then doing a recovery rather than a factory reset from the TWRP menu to replace all the files, including the potentially problematic build.prop. However, I didn't make a backup of the system before this happened (learning experience) and have no such image. Could anyone perhaps point me to a clean image for the Vivid that I could download and flash to my phone with recovery? Or otherwise shed some light on what could be causing the problem? I also realize there are various unbricking tutorials online, but after many hours of this I'm a bit too exhausted to follow all of those just to see if they work or not.

Edit: Upon further research I realize I can try to flash a new rom to the Vivid, but no matter how much I search I can't find a working link for a stock ICS .zip. There is a RUU .exe file from HTC but my phone can't get past fastboot, so I'd need to do this with a zip file. Anywhere I can get a working one? I could also try a custom rom, I just have 0 knowledge of those so don't know which would be a safe bet.

Would appreciate any help, and hope the post isn't overly long. Tried to give as much info as I could. I already spent a ton of time on both the root procedure and trying to fix this and would really like to hear professional opinions before breaking anything else. Thanks for reading.