I dunno about fully bricked, but it's well within the envelope of "hosed."
I'm sorry that I don't have a suggestion that might help to avoid future occurrence, but if the old board is still in a state where you can play with it, and you feel like trying one more thing (longshot), I got my DZ77GA-70K back by turning the PSU power switch off (or unplugging from the mains) and holding the power button on the case down for 30 sec. The power button the the motherboard would probably work, too, but I have not tried that myself.
Prior to that, none of the potential remedies I tried (including all you mentioned in your OP) would restore the board. Hope the new unit works they way it should.
My board is also "died" into on/off restarts loop after trying the bios 0057 to 0085 update from Windows 7 SP1 64 bit.
I have tried all official recovery manuals without success. But I have recovered by following steps:
- Power off the system. Disconnect the mains or turn off the switch on power supply (if exists).
- All SATA devices disconnected (not sure that is necessary).
- The PCI-E discrete card removed (not sure that is necessary).
- All USB devices are disconnected, PS2 keyboard is connected.
- The BIOS recovery jumper is removed.
- The monitor connected to onboard HDMI.
- The BH0057.BIO (can be downloaded from download center) bios is copied to USB disk-on-key 8GB/FAT32 (only one file on the disk)
- The disk-on-key inserted into USB2 front connector connected to onboard HH or FF connector (I don’t know which one HH or FF, maybe both are supported).
- IMPORTANT! The onboard battery is removed for few minutes. Without battery removing the recovery process will not start!
- Power on the system. The onboard POST-code display shows, the HDMI display shows the recovery process…
- Wait until “successful” message on the screen
- Power OFF, connect back the BIOS recovery jumper. Power ON.
After successful recovering I have updated the BIOS to 0085 from BIOS (F7)
and single file BH0085.bio on USB disk.