Here's a link. I posted only this link because of all the different Compaq Presario 2500 series notebook computers. Make sure download and install the correct BIOS. If you install the wrong BIOS it could render your system useless. This will get you to where you can download the BIOS and the utility to flash the BIOS.
http://h10025.www1.hp.com/ewfrf/wc/s...n&cc=us&dlc=en