If you're X3 BIOS works then you have little to worry about. However, if the BIOS isn't working you'll have to see if you have functioning FlashBIOS banks. Check your backup ROM (pwr + eject) then check On, On, Off, Off, Off if either boot to FlashBIOS then you can use that to flash to other banks and correct your mistake.
If you do not have a functioning X3 BIOS and your other banks fail to boot then you'll need a new chip/have to get it re-flashed.