Why won't my amp turn on?

I have a 2000 pontiac sunfire with a kenwood kdc 138 stereo in it and a 500 watt blaupunkt amp with a random 12 inch sub. My buddy and i tried putting in a new stereo deck so HE decided to be "smart" and jam my harness from my working stereo into the new one while i went to grab something. It blew the rqdio fuse in the fuse box and we didnt know it at the time so i disconnected all the wires and rewired the harness. I know what im doing, i rewired it all the right way, the stereo came on but the light on the amp did not. I checked the fuses for the amp and they're fine, i checked the ground, the power, and the antenna wire and they all checked out fine, and there IS power running to the amp. The sub was working fine before we did this and i tried the wires on another amp/sub and that didnt work either. So i dont think the amp is fried unpess they both are. Please help i want my car to thump again!!!! Ask for any more details if you need them. I used a 680 watt wiring kit from walmart.