I have had the sub and amp setup for a while now and it has worked great...It's a Kicker CompC 10" Sub/Enclosure with a Dual XPR52 600W Amp. Recently it started pulsing upon the start, but would shut off when the music turned on...now it won't even play music and the protect light is on. The car came wired for subs and I re-cut and got fresh connections and the ground connection is solid. Whenever I turn it on now, it just pulses slowly and the protect light is on. (I have only turned it on for a few seconds when the protect light is on)....Is it fu##ed? Or did I F##k it up? I replaced fuse and checked ground connection...
Check if the sub or lines form the amp to the sub are shorted, if not it's likely that the amp is done, pretty cheap amp too so I wouldn't be surprised.
You need a multimeter (less than $20 in walmart) if you get it I can tell you how to use it, pretty simple and quick, you could also go to a shop of course if you don't mind paying extra.