> The problem is I can't see anything, I have no video output. Consequently I am not able to change the Bios.
Clear the CMOS. That will restore the BIOS settings to their defaults. The default is to look first for a PCI video card and if it is not there then use the onboard video.
There's a little jumper (probably blue) next to the lithium coin-cell battery on the motherboard. To clear the CMOS, first disconnect power from the computer, then move the jumper to the other position, wait a minute, and move the jumper back.
You can then reconnect power and start the computer.