It might be worth pulling the radio out from the dashboard, pulling all the connectors out and then pushing them back in. See whether that makes any difference.

Other than that I think you will probably need a new radio because your existing one is faulty. It's not worth repairing them because you can obtain a second hand one from Ebay or a scrapyard for less than what a repair would cost.

If you do buy another radio make sure they give you the code!