Nexus 7 (2012) TWRP Restore fail, wont power on, black screen only

[captain_haddock]

Hi
I successfully rooted my nexus 7 WiFi (2012) and installed TWRP using the WUGfresh nexus root toolkit v1.8.9 . I went through my setup and installed / updated all my old apps following the wipe. All looked good so I wanted to do a backup / restore once it was set up. It appeared to backup successfully (no error messages) so I then hit the TWRP restore button and went through a restore. I saw an error message briefly (cant remember what it was !!!) and it did not restart. I then tried to power on but it no longer shows anything on the screen, no matter how long I hold the power button either alone or with the volume buttons. It was fully charged when I did this - if I connect to the charger I do not see the charging icon whether I hold the power button or not.

My guess is the bootloader is corrupted - is there any way out of this or is it permanently bricked? Can I reset the bootloader?

If bricked, would a replacement mobo be a cheap fix or do I need more that that?

Thanks for any advice.

 

[srkmagnus]

If you can boot into Fastboot then it's bricked. What could have caused that in TWRP I couldn't say. If this is the case there may now be any means to recover it without adb being able to recognize it via computer.

 

[captain_haddock]

I cant tell if it boots into Fastboot as all I get is a black screen. When I do plug the nexus7 into my win7 PC via usb, it attempts to load drivers but device manager just shows unknown device. Have tried same with Win XP too.

I tried installing apx drivers (Universal_Naked_Driver_0.72) to try nvflash but cant seem to get them to recognise the device.
If I remove the device I dont get an option to remove drivers and when I point to the driver folder, it says latest drivers already installed.

So there is some sort of life there but I am stuck in what to try next.