The most likely reason would be the new battery has fried the speakers themselves this is what happened to my Audi S7 when a new one is replaced sometimes the resistor is so old it can not take the amps given and fry the components Kicker audio has some the best and cheapest speakers on the market rn go to the Ds series car speakers find your car size and order then there is no need to upgrade anything else with this speaker's everything can be completely stock with this speakers and about 20-30 minutes to fix the issue. I hope this helps. :)