anti-theft issues (no problem with code)

I started the engine and it failed after turning over. That armed the anti-theft (I think). Found the code, put it in, but still the only thing working correctly is the radio. And the radio completely resets everytime I press on the brake pedal or turn the key. Is this a battery issue, a short, or am I simply not inputting the code correctly? Thanks, I couldn't find this problem elsewhere after searching for two days, didn't want to upset any vets.

sounds like a short with the battery. the only time the radio resets is when you lose power from the battery.