Hi there. I bought a sony explode car stereo. ANyways theres this
neighbor who said he'd install it for cheap. it's a mercury sable 1990
car. Since the wires of the car didnt match the wires of the stereo,he
decided to use a battery to touch the wires of the car to see which
ones are for the speakers. He uses a AA battery and said when he
touches the wires,the speakers make a pop sound and he would know
which wire was what. He touched the battery to the ground wire,and it
made a spark. Now I have a clock on the dash,it lights up but it
doesnt show the time, the inside lights dont turn on anymore,and now
the stereo wont power up when its connected. the guy told me he doesnt
know whats wrong and it could be a fuse but he doesnt know. i called a
few car repairs shops to ask whats wrong,and they just told me to
bring it in and i would have to pay to have them "look at it". this is
ridiculous,no one will give me information. the reason why i bought it
for a low price was because i didnt have lots of money,now i dont want
to pay a whole bunch more. please help me,thank you all.

Sounds like a fuse is blown. There's a fuse that supplies constant
battery power to the radio, inside light, and sometimes the horn, door
chime and anything else that works with the key off. It is supposed to
power the yellow wire in the Sony harness. I work at a audio/video
repair shop and we see this a lot.