The volume keeps turning down

Have you checked the LED states FAQ?

Sounds like the police have a warrant out for your amp.  Sounds like your amp is failing. 

This can be caused by a speaker or wiring fault, The first thing to check is short circuits at the AMP and speaker terminals. If you have an Ohmmeter check the resistance at the AMP terminals. Also, check to make sure that there is no connection between any speaker wire and building ground.

Are you using any speaker Volume controls?