94 Jetta electrical/starting problem

[fundiablo]

I'm working on a friend's 94 2.0 5 spd Jetta. Engine was rebuilt about 7 months ago. Car was running great until last week. Replaced battery, but then two days later, died again. Jumped the car, drove it to Autozone, alternator tested while running, was told it was reading ok. Car ran fine until day before yesterday. Battery died again, figured it was the alternator, replaced it earlier today, had battery charged, car still won't start. All interior lights and gauges come on, but car won't even crank. Going to check fuses now, but was wondering if this is a common problem with these cars. The car came with all service records (amazing record keeping) and the only thing of interest is that the previous owner had the ignition cable replaced in 97 and 02. The distributor cap was also replaced in 02, along with the battery. It seems from a lot of threads on here that starting/electrical problems may be common. Any suggestions?

[fundiablo]

I just posted a while ago. Checked the fuses, seemed ok. My friend told me the car's radio hadn't functioned since the engine was rebuilt and constantly read SAFE. The manuel that came with the car had a code to unlock the radio. Once we unlocked the radio the car started fine. I know it sounds crazy, but that's exactly what happened. Thge radio works now and the car starts every time. I don't understand and it's killing me. There is a car alarm, but is there is a starter kill as well? And if so, is it programmed through the radio? Where can I get codes read for the car?