https://www.experts-exchange.com/questions/10 … mada-1575D.html

You have to press F10 at the moment that, during boot, the white block appears in the upper right hand corner.
This only works if there is a diagnostics partition on the harddisk. Mostly this is the case. You can see it if you run fdisk.
If this diag partition is not there, you will have to boot from the floppys meant for this event. These floppy's can be downloaded at http://www.compaq.com.

Your BIOS is ok, but without the system partition or floppies to access the BIOS, you won't be able to make changes to the BIOS. Remember, if there is no system partition (shows as a Non-DOS partition in FDISK), the white block will not appear in the right corner. If it is not there, you need floppies as per joopv's recommendation.

So the problem can be that you have re-partitioned/formatted your HDD before installing Windows so now your diagnostics partition is gone.

Thank you very much 😀