How to recover from stuck at flash screen or bootloop.
I upgraded to 5.0.2 using the Blur OTA file as soon as it became available. It worked great. Then I rooted it with Chainfires Auto Root. Although it didn't go to the Red Android screen, once it rebooted I checked for root and I had root access. So again everything good to go.
Next I installed TWRP 2.8.5 Multirom Recovery, rebooted, still good. Next I flashed Multirom installer in recovery and thats where things went very wrong. It installed, took me to the ROM selection screen once, but after selecting "boot now" the phone stuck at "boot loader unlocked screen" and went no further. I tried a few more times but it was futile. So I thought I'd try and flash a "modded for multirom" kernel to remedy. Bad Idea... really bad. Now I lost recovery (not sure why, but I did) and only had access to adb/fastboot. Tried to fastboot flash back to KitKat and start over to reinstall the OTA and try again... minus Multirom of course. So I tried to return to full on out of the box stock with a stock image but it would not boot either. So I tried to ADB side load SuperR's stock 4.4.4 no luck there either. It failed at 84% everytime. So I tried his debloated and deodexed 4.4.4. And it booted but every two seconds it was force closing and was unusable.
After all this I began to think it was a done deal. No returning from this one. Then I saw SuperR made a fasbable zip of Lollipop. His "first attempt ROM". But it woud not sideload either failing at various points over and over again. Maybe if I could get that first attempt ROM to the internal storage I'd be good. There was only one ROM that booted since this disaster and that was SuperR's debloated 4.4.4.
Here is the fix...
1)Format everything System, cache, data, the works.
2)Fastboot firmware flash to attempt to get it back to a KIT KAT format.
3)ADB sideload SuperR's debloated, deodexed 4.4.4 Boot phone. (The phone fully booted but had major performance issues and FC's at this point but it allowed me to transfer the zip file of the "first attempt ROM" created by SuperR to the internal storage of the phone.
4)Boot to boot loader flash a custom recovery. Because your back to stock recovery after flashing the system image via fastboot.
5)Reboot to new recovery and do a full wipe. Now flash SuperR's "first attempt ROM" within recovery. Reboot the phone, and be patient. The first boot took 8 to 10 minutes but I finally got back to a working phone with 5.0.2!
I have had no problems since. I have the screen flicker problem only in recovery, nowhere else and the phone is saved from paper weight status.
Sorry about the long post just wanted people to know the conditions and circumstances of what shut me down.
I want to thank
@SuperR for all his work and the ROMs he created for both KK and 5.0 they are the only game in town ATM that I know of to provide this "means to an end" fix. Without those ROMs my phone would be useless.