I was making music the other day and suddenly my guitar became quieter and then just quit. I fiddled with the switches on the amp box and can't get it to make any noise or notes. I did notice this big wire that comes out of the amp box looks odd. I thought it may have been connected to this other wire on the floor, but I can't remember. I'm thinking of just taking everything to the repair shop. I'm due to go there to have my guitar strings tightened anyway. Is it safe to mess with those wires. My repair shop said I might have a toob amp and have to be careful about shocks.