Insane electrical problems; sub-woofer??

Just bought an 06 Tacoma. Not familiar with truck at all; it has a pioneer sound system with subwoofer that fits behind the seat in the regular cab.

The seller indicated he only used the sub-woofer a few times, but never had issues after using it; I played around with it and had the bass giving me a back massage in the garage. The next day I had electrical problems: turn signals not working, but hazards and other lights do; AC quit working (blower still did); speedometer not working. I took my ohm meter to the battery, read 12 volts, revved up the engine: no increase in voltage. Took to Oreilly's had tested: voltage regulator failed. So, a whole new alternator was cheaper than a voltage regulator; so, I put in a new alternator: absolutely no change with any issues. Took it back to O'reilly's they test the brand new (rebuilt made in China) alternator: same result voltage regulator failed. I had them bench test the old alternator: same thing: voltage regulator failed.

So, do you guys think a sub-woofer could blow up a voltage regulator (old or new)? I did have it set on active (but not loud) on the way to Oreilly's. I have checked (continuity) all the fuses they are fine; I checked some of the relays in the fuse box, they seem fine.

There are too many other quirks to list: I cant seem to shut off the radio without shutting down ignition; before I changed the alternator I could. Front hazards work, rear do not unless you tap the taillights. All lights are LED.

There was no rear license plate light so I installed one using the existing hot wire that was present. I did have a loose connection when I drove 2 miles to pickup electrical tape. The fuse did blow, I replaced it, hooked up the license plate light proper; tested, everything seemed fine, until I drove the next day.

I'm thinking there's got to be some loose connection or some relay I don't know about it. I believe there is a hazard light relay in the dash, could that be it? Is there some grounding wire that is loose?

Oreilly will give me a new alternator, but I don't want to install another one if its just going to get blown up again. Could it be that I just got a hold of a bad alternator?? Sorry to be so long-winded, there's even more, but I'll stop now.