Hi lfb6,
I want to add a note, after experimenting with updating my patched Dell Precision 7520 bios:
If AMT is enabled, these 2 values must be correct:
AmtWdAutoReset value=“Yes”
AmtIdleTimeout=“0x0001” ( I am not sure for name, but something similar)
If WdReset is not enabled, or Timeout is bigger than 1 sec (default is 0xFFFF),
then you will not be able to update your BIOS using F12 + usb with FREEDOS + .exe bios file.
The update will start, read the .exe file, and hang after rebooting
The only way to update is by using hw programmer
So my advice - always try to update your just-patched BIOS, using usb + .exe file 
Have a nice day