Battery Terminals Accidently connected briefly, Electrical short, control cables melted

I have a 70hp two stroke tohatsu that is a 2008 I believe. There was some short of short that causes the control cables to become hot and melt away the plastic coating. The battery sits in a compartment with a metal cover. I foolishly bought a battery that was too tall, and the when i close the metal compartment door, it caused the two terminals to be connected. There were a few sparks, but i quickly lifted up the metal compartment door and the sparks stopped. I thought everything was okay, but I came back 20 minutes later to find my control cables smoldering. I immediately disconnected the battery, but the damage was done. Is connecting those two terminals for seconds enough to cause this sort of damage? Or is there some deeper electrical problem? No fuse busted either, that was also surprising.

Battery is more than likely fried

Could that mean that the battery will cause this problem to reoccur? The battery will still hold charge and start the engine but I just can't move the controls

Sounds like the motor was connected with the correct polarity, but the boat ground ended up connected to the positive battery post for a few seconds. The throttle and shift cables connect between the motor ground (which was correct) and the boat ground (which was backwards). That turned those cables into heaters. While there may well be additional, as yet undiscovered problems (such as a possible burned-out rectifier/regulator), you will need to replace the shift and throttle cables for sure.

Thanks Paul, so it sounds like I need to take it to some sort of electronic spe******t. Do you think its best I take it to a Tohatsu dealership?

If you have mechanical skills you can do the repairs yourself

how can I be sure i have identified all electrical problems? its a duck hunting boat and I really dont want to get stuck miles away from the ramp in the wintertimr

Has engine been run since issue? Check all wiring under the hood . Test the rectifier with a dvm, If engine runs,see if battery is getting charged,should be 13.5 volts or slightly higher