Try to :
1) read the manual to find where are the two pins, which are used to reset BIOS
2) Use a screwdriver to momentarily (1 second) short these two contacts to reset BIOS. For good measure, also remove the board battery (read manual to find where it is) and wait 10-15 minutes, then reinsert the battery and try to boot again.
3) If this didn't help try to "flashback" BIOS - read the manual if your board allows it and how to, and use the correct type and format USB stick for that.
4) If flashing a new BIOS doesn't help either - or your board does not support "flashback", you may try to use USB flash device (sold on Aliexpress for $10-15) to do the same as flashback, but using the special clamp for the BIOS chip. You will need another PC or laptop for that to host the USB flash device.
5) If all fails, you can try to RMA the board, or buy another one. You will need to re-activate Windows as it locks activation to the board (possibly buy a new license if activation with the original code doesn't work - Microsoft now claims the license is "for one install only") - so this is a last resort. If you had activation tied to your Microsoft account - it could be be a little easier. Or use without activation.
6) Where it's not needed, don't use passwords.
