it was probably hooked up right, usually if something is wired wrong you will know it immediately, besides if they replaced it a bunch of times already then there is no way they screwed it up more than once, its probably just a shitty product, that or your friend is seriously boomin that shit night and day every second, a lot of amps(especially budget amps) can't take constant high loads especially over like a 20 minute(or longer) commute
all amps will shut off when they get too hot to protect circuitry and prevent fire, but its a circuit breaker that does this so every time it shuts off, the next time it will shut off easier and easier
they probably wired it through the fuse box so the amp will turn on with the car... not the radio, so even if the radio is off the amp is still on and will still overheat because power is still flowing
all amps will shut off when they get too hot to protect circuitry and prevent fire, but its a circuit breaker that does this so every time it shuts off, the next time it will shut off easier and easier
they probably wired it through the fuse box so the amp will turn on with the car... not the radio, so even if the radio is off the amp is still on and will still overheat because power is still flowing