I wanted to try Dhacker's Kitkat 4.4 soooo bad, but my RAZR M was on the newest OTA and un-unlockable. I thought hmmm... if the bootloader unlock exploit targeted the TrustZone partition and the OTA patched out the TZ exploit, maybe I can downgrade the TZ partition to bring it back! So like the idiot that I am, I "dd" the old tz.mbn into /dev/block/mmcblk0p7. Attempted to reboot to see what would happen, and well, brick happened. So yeah, don't do that. It's so dead, it acts like it has no battery. Obviously, I'm a moron and should leave the hacking to the hackers.
Anyway, is there a way to JTAG it back, or is my only recourse to use it as parts to fix a phone with a cracked screen or something?
Also, I'm not smart enough to know why it won't boot with a downgraded TZ partition. Just to satisfy my curiosity, Is a hard-brick what happens when the "chain of trust" is broken? Could it have worked had I downgraded every single partition involved in the chain of trust, or am I super far off base?