Sundown SAZ1500 stuck in slave mode??? .5 ohm capable?

[BigDaddy13440 3]

I picked up a used SAZ1500  for $50 off Facebook Marketplace, guy thought it didn't work. Figured I'd send it for repair, and be into a great amp for under $200. Got it home, fiddled with it, and found that none of the controls work, but if I run a signal through the slave input, it does indeed work. So it's stuck in slave mode.

Does anyone know how to get it out of slave mode? I'd love to be able to set the gain properly, dial my system in the way it should be done.

AND.... with proper electrical, can this amp be run at .5 ohms? Good ventilation, dual runs of 1/0 to dual 1/0-1/0 reducers at the amp, 250 amp alternator. Am running it now at 2 ohms to my (2) dual 2 ohm subs, if the amp will do .5, I'll do some rewiring.