Disconnect all speaker connections and rca cables. Leave power, ground and remote wires intact. Try turning on again. If you still have a protection light your amp is faulty. Hopefully you have warranty. Time to doub .A thumbs up would be greatly appreciated if this answer is helpful to you.

Most commonly that means that somewhere there was an arc in the electrical either the pos or neg going into the amp or rcas or its the speaker wire from the amp to to the sub itself look especially for little wires touching opposit polarity wire (like a little +wire has moved and touched a - wire)