snap crackle and pop through the speaker even when radio is off
Sounds like something is seriously mis-wired or something got pinched. The only thing you can do is pull the stereo and start checking wires. You may want to pull the speaker out and put a volt meter to it and see which one is getting power from who knows where. The stereo usually has one HOT wire going to it to power up the internal clock. Maybe that wire melted into one of the speaker wires.
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