"engine power reduced" and head unit not working...

[Nosho47]

I installed my amps and when I tried to start up my Tahoe, the "engine power is reduced" sign comes on. I know for sure I didn't cut through or pull any wiring to cause this. The weird thing too is that my head unit does not work at all. I checked my fuses with a dmm and its normal. I have also checked the ignition wire going from the head unit and there is no power going to the fuse. Does anyone have a idea what it could be?