Amp does not power on, flickers when cable...

Question

I bought a Kenwood KAC-8403 amp a couple of months ago, and hooked it up to my car / sub. There were existing power / ground lines in the car from the previous owner. Everything worked fine until a couple of days ago when I hit a bump, and my sub and sound went out. Now the amp wont power on, andthe only time it shows any power is when I disconnect the power cord. Any ideas?