1996 5.8L Pro Boss Gt-40-Electrical? No gauges, no ignition beep, just dead?

I have a 96 MB Sports 5.8L Pro Boss GT-40 351 engine. I ran it yesterday and heard a strange engine tone. Lifted the engine cover and found a drive belt from the alternator had broken. I replaced the belt and ran it for 20 mins when I noticed a lot of heat from the engine. Turned the engine off to allow it to cool, but when I turned the key I got nothing. I have no ignition beep when key is turned to first position. The gauges do not read and engine will not crank. It finally started after 30 mins and drove it to the dock. After turning off, I tried to start again and found the same problem, but this time it's dead for good. I have 2 batteries that both have good power and have had no problems up to this point. Is this an electrical problem, or could this be connected to the alternator belt? Anyone have a similar experience?

I'd bet electrical and just coincident with the belt. For a start, try these:

Check the main battery feed supply and the ground. If ok, move on and verify the relays work, if they are ok, check the fuses.