You can reset the BIOS by detaching the cmos batter for 15'' or moving the 'clearmos' jumper from position 1-2 to 2-3 and then repositioning it to the default pins after 30''.
I had your problem once and sorted it out that way. See your motherboard manual for specific instrucrtons
Unfortunate that this happened, as what you most likely now have is a "Soft Bricked" device. If that's what happened, recovery is an absolute PIA.
Then you'll have to locate the serial console pinout on the motherboard, connect one end of cable Mobo and other end to a running system's Serial Console. If all goes well the cu(1)() interface will show you the boot process and then you can try and figure out how to interrupt boot and flash a new BIOS file.
If you choose to go this way, be sure to do a lot of reading about "Bricked Recovery" on the *WRT distros help pages.
DISCLAIMER: I've only done this on modem/routers but never on a full-fledged computer. Whether Serial Recovery will work on a Laptop is beyond my experience.
I think your only hope is something like this:
You have to make a usb boot drive with the correct BIOS and it has to be setup to flash automatically.
You will have no video only beeps to go by.
To use this method you need to find out the BIOS manufacturer and use their procedure.
The above Phoenix BIOS recovery method is only for Phoenix BIOS. You need to find the proper procedure for your BIOS.
Sorry I recommended that you use a custom bios. My similar flashing experience was successful.
I have used a custom bios with HP laptops from the same era with cell modems.