Volkswagen: 1998 VW golf, serpentine belt tensioner, golf question

Question
QUESTION: I first notice my non stock cd player was blinking when my car was off.  I haven't driven since yesterday so I had to check to see if my battery was drained.  My key remote did not work so I manually unlocked the door.  Then the car did not start.   I tried to jump start the car but it made an unusual sound rather than the sound the car would make when it's trying to start.  Then we heard this constant beeping noise, but if we open the door it would stop.  Yesterday when I was driving I notice this burnt plastic scent.  I made the decision yesterday to stop driving my car until my serpentine belt and tension roller replaced.  I'm not sure if my impending repair had anything to do when this odd problem.  
thank you

ANSWER: When the battery gets extremely low, the electronics will do completely unpredictable things.  Not sure about the smell.  Was your belt seized?  If so, the alternator wasn't moving and the battery would have run down.  Does it start now?

---------- FOLLOW-UP ----------

QUESTION: I'm not sure about the size of the belt and the car does not start.  I just noticed that the alarm light by the lock is blinking abnormally.  Do I have to change my battery or can I get it to charge somehow.  My cd player is rigged to turn on without turning on the car because of some weird defect in my ignition.

Answer
You've got a lot going on that may or may not be related.  The radio should have power inputs for both switched and unswitched inputs.  Is that how it is wired?  Even so, a CD player shouldn't completely drain a battery unless it is on it's last legs.  You'll need to charge up the battery or jump the car.  With the battery that low, you may need to charge it for a while before it will start.

Why are you changing the serpentine belt tensioner.  Is it noisy or seized?