Hmmmm. I've only heard stories of BIOS flash disasters. I've never had one, but when I flashed the BIOS on my VT-503+, I was warned of a few particular dangers. Here they are (for me):
1) Spell everything correctly. Use the proper case (as in capital letters). For example, my floppy (courtesy of format a: /s) contained the flash utility and the *.bin file. I typed this in:
flash73 je4331.bin /Py /Sy
I can't remember what /Py is for, but /Sy gives you the option of saving your old BIOS on the floppy.
2) When the flashing process begins, leave the computer sit. Even when there is no activity, let it sit. After a long while of nothing, I had to press either F10 to exit or F1 (or F2, can't remember) to reboot. After that, smooth sailing.
I guess my main question to you is, did you spell everything correctly, using proper case?