Subs and amp dont work
His amp probably blew your fuse. Check that you have 12V at the power connections. If you don't, then find the fuse in your positive wiring to the amp. If you do have 12V to the amp, check your remote power up also has 12V between that and the negative line when your head unit is on. If it doesn't, then it's probably an internal fuse in your remote switch on line inside your head unit caused by a fault in your friends amp. This is normally accessible at the back of the head unit.