I'm working on my first install and screwed things up. I created a spark on a live wire while installing a new powered subwoofer and messed up my 4 channel amp that drives the door speakers. Sometimes the amp will work and the electrical system reads 12+ volts on my multimeter. When the amp doesn't want to work, which is intermittent, the electrical system will read 6.5 volts. If I disconnect the ground cable from the amplifier I get a reading of 12+ volts again. I have checked all connections, checked resistance on all power wires, checked the ground, and have narrowed the problem down to the 4 channel amp. The amp is a JL Audio JD400/4 and does not have an external fuse. Would you recommend repairing or replacing the amp? The amp works sometimes but not for long. I have decided to disconnect it to prevent a possible fire. It's under warranty but to be honest I'm the one who messed it up so I doubt it would be covered. Any advice would be appreciated!