|This is my informed GUESS based on what you are reporting.|
What you are experiencing could be due to your BIOS CMOS settings being lost or scrambled due to the motherboard coin battery voltage having dropped below 3.0 volts.
Normally you would in that event get a prompt to enter F1 to continue or F2 to go into set up. However from your message it seems your BIOS is password protected and you need to provide a password before it will allow you to access your BIOS.
Do you know whether your BIOS was password protected? Do you have the password?
You could try and remove the coin battery for a while , then put it back and try again. This may reset the CMOS settings and you may on the next boot get the F1 / F2 prompt allowing you to go into the BIOS and correct the settings in there or at least set them to default values.
NOTE - This is an informed guess on my part and could be wrong as I am not 100% sure. You could wait and see if anyone else has any other ideas.
☺ When everything else fails, read the instructions.