How to check if an amp is blown??? Options

[Camax333]

All of a sudden my amps and subwoofer don't work. The power connection is okay because when the car is first turned on, the amp blinks red (protect) and the subwoofers light up, but then the light goes off and the subwoofer does not work. The rem wire is also okay because when the headunit is off, the subwoofers don't light up and when the head unit is on, the subwoofers do light up. Lastly, I think the ground wire is okay because when the ground wire comes off it the protect light usually comes on. So is my amp blown?? How can I check if it is blown, besides tryin to attach a different amp.