I'm fairly certain the circuit board won't spoil from juice leakage. The more likely scenario is the juice is sticky and it's impeding the buttons from functioning properly. don't give up. clean, clean, clean over and over.
If it comes down to it, i'm sure there is a way to solder new wires for external buttons and you can frankenstein a new box.
If it comes down to it, i'm sure there is a way to solder new wires for external buttons and you can frankenstein a new box.