If a battery is low on power, will an amplifier not turn on at all? I've got a bad battery in my boat, and when I hook up a charger, everything else works but the amp will not turn on. Im hoping the battery is all thats wrong.
The boat electronics may have a lower turn on threshold than the amplifier. So give the charger more time.
Don't trust the charger volt meter. Verify the battery voltage from a multimeter or the helm volt meter gauge with the charger disconnected.
Check the fuses in the amplifier chassis.
Check any main DC breaker wiper or master fusing as they can get a little sensitive with low voltage. This is a regulated amplifier on the supply side so it will attempt to pull more current as the voltage drops.
Do manual checks on the main connections and grounds at the battery and amplifier terminals. It might look okay but not pass the tug and wiggle test.
Do a hard reset by disconnecting both power and ground, let it sit for 5 minutes and attach the ground before the positive. Try it again.
Check your owners manual and see if you are getting one of the LED diagnostic codes.
If nothing materializes then pull the amplifier and get it bench checked.