Disconnect the speakers first as already suggested. This will either point to a cause, or eliminate a cause. If the amp then starts acting normal, you want to start snooping your speakers and their wiring for shorts, or abrasion where the wiring is grounded somewhere.
If disconnecting the speakers does not cause the amp to go green, turn the stereo on and measure the voltage at the amp power terminals. It needs to be at least 10.5 volts to even turn on, and to run reliably, you need to measure very close to a solid 12 volts. If you measure less than ideal, you need to check every connection on your power wiring. You also need to measure voltage at the battery to see if you have good solid voltage there too.
DO those steps and get back to us.