Rass66

Help guys!
I just bought a 94 Barracuda the other day. Yes, like a moron I didn't start it first. They had a battery charger on it when I got there and it would just click when you pushed the button. THey have offered to give me my money back but I would rather have the boat...
I put a new battery in it yesterday and got the same response. Just a click and sometimes not even a click. I took the starter button apart and cleaned the contacts and there is power going throught the switch so I'm sure it isn't that. But the positive cable coming from the battery goes into the "brain box" but the red cable coming out of the box and to the starter doesn't have power even if the starter button is pressed.
Has anyone had this problem or could someone give me some ideas?

(The motor is free and can be turned by hand)

Thank you for any help or advice

Troy