Recover mac mini broken BIOS (mac mini displays nothing)
If you are entirely sure that the computer is starting up with a connection to a monitor, then this is a problem with the disk format more than likely. This will make it so that the Mac will not be able to boot into recovery either. You'll need to go to an Apple retailer to ask them to reformat the disk for you, or perhaps it's possible on your own. I know that apple likes to ensure no third-party computers register with Mac OS X so they format the disks in dumb way.