|Dunno if the PC speaker works but it must have a beep code to diag it unless you do other diags like swap or motherboard diag board or such.|
Test the voltages from the PSU or swap it.
Try to get the board to beep. If it has power and no beep without critical components then get new motherboard.
We suspect the reason it has sat in the closet.
1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.