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. :)
Once your iPod is connected, you can go to the devices icon on iTunes and select it. Then, go to the sidebar to visit the Music section. From here, you can just turn on the option to sync your music. You can choose to sync the entire library or select the playlist, artists, or albums of your choice. Hope this Helps. :)
Watch this video on how to replace the motor https://youtu.be/VeCiivPt7hk. And here is the part https://www.ereplacementparts.com/worm-gear-p-1106526.html. I hope this helps. :)
There is really no cheap way to fix this. It would be your board going out. Personally I would buy a brand new one it would be the same price to buy one than to fix it.
I would say it would more than likely be a messed up LCD replacement screen because those screens are so stupid fragile and always mess up in shipping I would try the screen first.
This is the same thing that happened to my Google Pixel 7 Pro what fixed mine was the charging port was completely bad and I unknowingly kept plugging it up thinking its not my port by me doing that I fried my battery and the last bit of my charging port. So overall check the charging port and battery. Hope this helps. :)
The most common reason for this is dust and other materials getting under your pad you can dismantle your computer dan blow all of the components out with an air can. Hope this helps. :)