Single clunk sound when attempting to start. Help!

[Moonfire]

Hello all. This is my second day owning my 89 and first day of having an issue. Happy to be here and hopeful I can figure this out, I'm not giving up this early!

So, I bought the van, it seemed fine then the dreaded Christmas Dash scenario happened right as I drove off(go figure). I drove it about 100 miles today and then I stopped, loaded the van with some stuff then tried to start it again and the van had a no start(or clicking sound). I jiggled the key an tried again turning the key quickly and it started. Now I am at a friends house stranded. I go to start the van, Christmas dash illuminated, and all I get is a single clunk sound under the drivers seat. It is almost as if the starter is not getting any power and it's driving me crazy. All the fuses under the glove box are fine. The van has a secondary battery and power inverter in the back and it was all professionally done(I have the receipts). There are random wires under the dash going nowhere and an aftermarket sound system and I think an alarm. Essentially I'm dead in water and freaking out.

can anyone help me or put me in the right direction? I'm in the Sacramento area an open to havin a fellow van owner come help. Hope I figure this out and I'm not roflroflroflrofl out of luck and money.

thank you