Amp turning off at volume

[Dexter Chaos 14]

I worked this past weekend. Drove to the track and parked my car on friday afternoon. I went to leave tonight and when I would turn up volume to my normal listening level the red light would come on and my sub would not work. When I parked my car on friday everything was working correctly. Any thoughts why this would happen? We did get some pretty hard rains but I have had no issues with this previously. I have been running this set up since january.  I have not had the chance to check voltages yet but any direction to why the sudden change. My current battery is just the standard car battery I purchased from sears in december. Just confused.

[MikeMartel 64]

If the amp is going into protect it will either be a voltage problem, or possibly the subwoofers are blown/shorting out.

[Dexter Chaos 14]

If the amp is going into protect it will either be a voltage problem, or possibly the subwoofers are blown/shorting out.

The sub still works at low volume. Could it still be blown?

[Impious 1,476]

Just have to start by process of elimination.  Start simple.  Check cables make sure everything is still tight & secure, including ground cable.  Check voltage under load.  Move on from there to the subwoofer.  Check impedance & continuity @ different excursion levels.....i.e. push & hold the cone inward & outward.