Silverado 2003 radio electrical issue

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I have a 2003 chevy silverado 1500 and the radio is not working. The previous owner installed their own aftermarket radio but took it out when he sold it. There were just a bunch of cables without a radio in the truck. I bought the original radio from somebody in town and plugged it in. The radio doesn’t fully work. The dimmer seems to work on the radio and half of the buttons light up when I have the dimmer on max. There is more.. on the dashboard I don’t see the battery gauge light up when I turn the dimmer on. Also the fuel gauge drops sometimes turns on and off. When the fuel gauge turns off, the orange light at fuel gauge turns on and the fuel level goes to empty. The oxygen sensor bank 1 sensor 1 also doesnt fully work. The check engine light is on and I checked the wiring. I checked the live data, and whenever I start the car all the oxygen sensors heater banks values goes from 0 to 1, except for bank 1 sensor 1. Thank you for reading. - Bart