Well, before I went for a DMM or multi-meter, I started off as basic as possible. If the LED's turning on, then a burnt fuse isn't the problem. It wouldn't even turn on at all, correct?

I discovered the power/ground/remote wires were all fine when I swapped the sub amp and Alpine's wires - - the sub amp worked, while the Alpine's LED lit up briefly, then dimmed immediately. Keeps doing the same thing, but no 'pop' or any sound at all.

I'm starting to think that the amp's fried...what else could be causing this problem if the wires are alright? It worked fine for two years, I haven't made any abrupt changes in the wiring or my car since.