Hi!
I'm new here and let me start by saying I know very little (or nothing) about electronics, other than how to plug 'em in and tweak the knobs. Now that I've gotten that out of the way, here's my problem:

I have a Boss Metal Zone MT2 that I bought second hand about 6 years ago (could be more; my memory's terrible). Out of the blue, it's no longer registering a signal. When I press the pedal down, the red light doesn't come on to tell me the distortion's working and, more importantly, the distortion doesn't work

I have an AC adapter (Boss) for it and I use quality cables that are all working. There's power going to the unit; I've tested the outlet with other gear.

Any thoughts out there as to what I can do/check next? I'm pretty capable when it comes to learning on the fly. I've taken everything apart and it all seems "ok" (all the wires and such seem to be connected, still). I don't have any electonics meters to check stuff out, but if you could suggest some, I'd be prepared to go and get them to test it out (provided their combined cost wouldn't be in excess of the cost of a new/used Metal Zone).

I know it's not the greatest pedal in the word, according to some, but I like it nonetheless.

Thank you for your time!

It may be the on/off switch is worn out. Do you get your clean sound when the effect is off? The switch is a likely culprit. If you have to get it fixed, it may cost more than replacing the whole pedal. So, you may want to use this pedal as a "test bed", to learn to work on your equipment.

Is there a way to replace the switch myself? Or would I need to order a part that likely costs almost as much as a new pedal (same old argument)? If I can get a replacement part from say, an electronics store, I'll try it myself (I'm not the greatest at soldering, but the best way to improve is to practice)

Try posting this question, in the Guitar, Amps, and Pedals section. That's where most of the action is. And there's a lot of people with much more knowledge than me. They may know of a good source for the switch. Also, they may have a better diagnosis.
Chances are that you can find a good switch fairly cheap. It may not look good. But, there's probably a good replacement available.

Smae thing happened to mine, not that i use it much, but when you turn it on the light comes on, but you have to crank every knob to hear anything, and even then its really low. only boss pedal i ever had that crapped out on me..

Did you try it with a battery?