hello all, i was tinkering with my panasonic aftermarket head unit while attempting to install a subwoofer amplifier in my car, and i think i may have shorted something out - the head unit won't turn on at all. i double checked and re-wired everything from the head unit to the harness and it still wouldn't work, so i busted out my stock radio and plugged it in, and to my dismay it worked just fine. today i exchanged my panasonic head unit for a new one, brought it home and wired everything up, and it still wouldn't turn on at all. i tried the same head unit in my brother's accord, plugged it into the harness, and it worked perfectly. i tried to plug my brother's working alpine head unit into the harness in my car, and it wouldn't turn on at all. again, the stock radio works every time i try to plug it in. i have had the panasonic head unit for almost a month, and it was working perfectly until yesterday.
other possible items of note: ever since the head unit stopped working, my dash clock has been noticeably dimmer. also, (this is probably unrelated) about a week ago my tachometer started reading slightly lower than the actual rpm's (judging from the sound of the engine).
i am quite new at all of this stuff, so any help would be much appreciated. thanks!