V50SP mainboard setup access blocked

Anyone knows how to unblock setup on this mainboard?
I know about control alt esc but this is disabled.
The pc is an acerentra or something, front plate mentions this.
Acer europe sends me to acer africa and so on, talk about support.
I know this pc is old, it serves it´s purpose and all i need to do is a
harddisk replacement.
But it keeps booting from either floppy or cd rom, even while the harddisk
is detected properly.

Bart Bervoets