The only real troubleshooting you can do with a radio is to check that all connections are properly secure and to check the power. Typically there is a fuse on the power wire that you can check, but since you said it powers on the fuse is most likely fine. From there you can check the voltage to see if the stereo is getting a full 12 volts with a multimeter # PT89ZR. If not then the power source is the issue.
If it is getting a full 12 volts then the stereo may have internal damage and... view full answer...