i bought a used amp and it arrived in the mail today. how can i test it to make sure its not DOA? it has indicator lights on the front, but when i hook up the power, ground, and remote wire to it and turn on my headunit, no lights come on the amp. is this a correct way to test it? i don't know much about car audio and will probably bring it to a stereo shop to get it installed. this is a bigger amp than the one i'm replacing b/c my old one was having problems.