2001 Volkswagen Jetta battery/radio/clock

The battery in my 2001 Volkswagen Jetta, 4 cylinder, 2.0L, died this week. I purchased a compatible battery from a local auto shop and replaced it. The car starts up fine and runs the same as it did before the battery died. However, a few other problems popped up. The radio now doesn’t work at all. The 2001 Jetta has a safeguard feature that requires the radio to be “unlocked” after the battery is replaced – but nothing shows up on the screen at all. I checked fuses (that I believe are) associated with the radio, but can’t find one that is blown. I took many fuses out and put them back in, with no avail.

Also, the clock and the digital trip odometer do not stay set. For instance, I set the clock and when I turn off the car and then turn it on again, it returns to 12:00 and the trip meter is back to 0.0. If I turn the car off for just a few seconds and restart, the numbers stay. But if I wait more than 30 seconds and restart, all is lost.

I thought that this could be an alternator problem. But I followed an alternator test (taking the negative electrode off the battery for more than a minute and the engine continued to run), and it worked fine.

Ever heard of anything like this? Any suggestions for me to fix it myself? I’m at a loss...

Thanks for any help you can provide!