i bought a car with this head unit, drove it home listening to music then when i got home and started digging threw the back trunk and saw that the guy hook up an amp to the speakers in the car, and saw that the ground was loose so i took it off and tighten it then fixed all the wires. I went to turn on the car to adjust the stereo then i realize the stereo was flashing saying PROTECTED...does anyone know what i can do to fix this problem...i unplug the head unit, reset the stereo, and took off the battery still the same...