ENIGMA97

Hey I was wondering if someone might be able to help guide me in the right direction with some issues I’m having with my electrical components. My brake lights, gas gauge, fuel door button, and nav screen all have gone out since I recently had replaced my battery. My battery died a few days after installing an amp in my car. I have since unplugged the power source to my amp. I’ve had my fuses checked and they look to be good. I’ve had an alternator and starter test done as well at Autozone and both those tests came back good too. Its the oddest thing, my Nav display does come on and works as far as my climate controls, but Navigation screen is pitch black. Does anyone have an idea what else it could possibly be? Any help is appreciated thank you!