Mark

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!