Precision M6800 BIOS Update A26 - Hangs on " Sending Intel(R) Management Engine Firmware "

I've updated the A26 Bios version on 4 different Precision mobile workstations with no problems. For this ONE particular unit, the first part of the BIOS update works, then it goes to the screen " Sending Intel(R) Management Engine Firmware Update " and stalls at progress of 0%. The keyboard is unresponsive, and after letting it try for hours (even overnight), it's still stuck on 0%. To restart,  have to disconnect the power supply and remove the battery. Other things I've tried:

1. Removing AC Adaptor, the battery and removing the CMOS battery, clearing CMOS. Same result when re-flashing

2. Replaced the CMOS battery. Same result when re-flashing

3. Tried flashing from the F12 startup menu, update by selecting the "M6800A26.EXE" BIOS file on a USB drive. Same result when re-flashing

4. Downgrading all the way back to A06, then trying a few in-between, like A16. Same result when re-flashing

The laptop boots and functions, but the bootup process takes about 5x longer. And there's an error at the top left of the screen right after the first DELL logo, saying "FW Status Recovery Error" The IMEI drivers won't install in windows

 Windows 10 Pro.

Am I out of luck? I've googled the heck out of those error messages, haven't seen any solutions. Some comments claim that the intel firmware has been corrupted and there's no hope to recover it.

Help!