I hope you have an old PC laying around with Windows XP or Vista 32-bit on it. Windows 7 32-bit might work also, but anything newer and that software...
I've updated my original post to bit a bit clearer, but the gist of it is:
Go into service mode as you normally would. When the password screen pops...
Could it be that it had a Lexmark toner cartridge installed, not a Toshiba cartridge? Or vice-versa? I'd think the EEPROM would be coded differently....
There certainly isn't a lot of detail in that bulletin. It would have been nice to know what changed. Or would that be too much like admitting there...