amp turn on ineffective

My friend and I are trying to hook up his system (power acoustic amp with a 10" kicker, square version). we are using an output converter so we hooked the remote to the radio fuse and the power wire is hooked up to the +battery. only thing is, wen we touch the ground wire onto the chassis we get ALOT of spark and the wire gets HOT, the amp turns on n off, and the sub is making some sort of heartbeat motion like its trying to fight for its life. we already tested the amp at the store and it worked just 2 days ago. and the sub works too. if anyone knows whats wrong it would be very beneficial to us. thank you for your time.

How big is the ground wire to the amp?

How big is the power wire to the amp?

How big is the fuse installed in the amp power wire at the battery?

I would put a 30A fuse in it and hook everything up correctly (ie securely ground the ground).

Then, try it again.

It's possible that when you are just touching the ground to ground that you arn't getting a good enough ground connection.  Make sure you scrape away the paint wherever you are grounding so you will get the best possible connection.

Also ive found it a good practice to hook up the ground first. power second without the fuse. than the fuse last.

for testing purpose you can jump a wire from the batt to rem on the amp after all the connections are made(you can fuse that wire if it makes you feel better) if the amp is fine than the rem will only draw what it needs which is not much