I went to the Gateway site and was surprised that they didn't have much choice in BIOS versions. So this is what I suggest:
1). when you flashed to the new version, almost all flash utilities either back up the previous BIOS version automatically or at least ask to do so. If a backup copy was created (and you saved it) it can be restored by directly flashing to it.
2). Contact Gateway support, tell them that the most recent BIOS bricked your box, and you need access to the previous BIOS version (and you not only want it but YOU WANT IT NOW!!!!!!!!!!!!!!!).
3). In most BIOS there is an option to disable the splash screen. This won't get Gateway back, but will dump the Acer logo.
And it would REALLY HELP if you would give the model number of the machine.