It doesn't look like any user-controllable options have changed in the BIOS, but there may be other fixes. Too bad we don't have a revision history. Thank you for the images.
I have never hot-flashed a BIOS before, but I think this is what I'd do,
1) On M919 motherboard with non-flashable BIOS, partially remove the BIOS so that it is just connected.
2) On M919 motherboard with partially connected non-flashable BIOS, boot the system without a boot disk in place and no harddrives. When the system requests the user to insert a diskette, swap out the M919 BIOS and put in the HOT-433 BIOS, then insert a DOS boot diskette.
3) Run the Uniflash utility and flash the BIOS to the M919 1998 revision.
Is it possible to just flash the HOT-433 BIOS inside the HOT-433 with the M919 1998 BIOS? Once flashed, quickly turn off and move the BIOS to the M919 motherboard?
Which method works? Both?