my buddys got a 2000 z71, and he was changing the oil in his truck, he reset the engine oil light. left it alone. came back an hour later and now his stereo isnt working. he said "i turn the truck on and the screen stays black until i hit the clock button, then the clock comes up for like 20 seconds then goes off again, but i can't turn it on." he has an after market system hooked up to his stock stereo. so hooked up to the stereo, is the rca cables, and the remote wire. its wierd. any suggestions on what the problem might be?