My car wont keep a charge

Recently tried to install a aftermarket radio. Forgot to unpluge batter cables, so the orange and ground wires touch causing them to melt under the dash borad. I didnt burn the module because I ca still start the car. I took out the audio fuse so there was no power to those wires. Now my car wont stay charge. Some time it will stay charege for a couple of days to a week. But then come mornig thiers only a little juice. Everything is good started battery altenator. What could it be? Did I possible melt wires? Or is my battery messed up. Shop says battery is good. Can't trust them though