While recovering using a back up in twrp my M9 bricked. How can I fix it?

[AC Question]

While recovering using a back up in twrp my m9 bricked.

Phone details:
One m9
HTC__031
unlocked bootloader
s-on
2.10.401.1
So while trying to recover my phone to stock using a twrp back-up, it got stuck at 1%, it stood at 1% for over 15 minutes. So I reset it (power + vol up/down, can't recall). Now when it boots up it gets to the exclamation screen, using power + vol up I get to android system recovery <3e> (stock recovery I guess). I tried update from adb with several files I found on xda and even htc's own site to get the stock 5.1 rom back on it. I tried flashing twrp while in the bootloader but my pc only recognizes my phone as android, when I chose the apply update from adb in the stock recovery I was able to use fastboot to sideload the files I found. I'm now stuck with a phone that doesn't accept it's own correct stock rom, doesn't have a custom recovery, and I also get an error in the stock recovery:
Write host_mode error
Handle_cota_install: Can't mount /sdcard, 1 times
Handle_cota_install: Can't mount /sdcard, 2 times
Handle_cota_install: Can't mount /sdcard, 3 times
Handle_cota_install: Can't mount /sdcard, 4 times
Handle_cota_install: Can't mount /sdcard, 5 times

 

[Rukbat]

Try flashing a stock ROM. Then install TWRP. Then try restoring the backup. (If you find that it won't even flash the stock ROM, you could have a hardware problem.)