Three months ago had to have 2003 Honda Accord (with 150,000 miles) towed dealer because it wouldn’t start. The battery cable was corroded and was replaced. It now has begun to corrode again. The radio stopped working at the same time.
Some batteries leak their acid electrolyte, likely due to a tiny crack in the case. Your cable will probably continue to corrode until you replace the battery. In the meantime you can delay corrosion by wiping down the battery, its terminals, and connections with a rag moistened with a solution of baking soda.
The radio is a separate issue. Maybe there is some kind of antitheft security code involved.
Review your owner’s manual.
While you should certainly just look at replacing the battery you can also get battery terminal protector at auto parts stores. It is a spray on coating that is supposed to protect from corrosion.