I got a 1996 Buick Regal. Three months ago, the belt inside my power antenna system broke, so its electrical motor worked continuously (even while the car's engine was off). After a while the ABS light turned on and stayed solid for 2 days. The next morning I couldn't start my car. Whenever you turn the key to start it the whole instrument panel would light up then went completely dead. Thought it was a dead battery, so I replaced the battery and fixed the power antenna. The problem solved. However, couple of days ago the same process happened! ABS light stayed on and after a while I had a dead battery. Any idea what the problem is and how I can fix it?

Sounds like your alternator isn't putting out enough voltage. Have it tested.

You have alternator problems, caused by the dead battery. I sure hope you already disconnected the faulty ariel. Now it's time to replace both alternator and battery. An expensive lesson.