Battery gauge maxed after battery issues
2000 Cherokee Sport 4x4 4.0L
About a week ago, I took an early trip out of town to Charlotte so my wife could attend orientation at college. I was dead beat from not sleeping well the night before, and parked in the school parking lot and fell asleep for an hour or so. Woke up to realize I had left my lights on, and the batter was dead. Got a jump and while the car started each day over the last week, in the mornings it was a very slow start. Yesterday morning, it wouldn't turn over. Today, I decided to take the battery connectors off and clean them. One broke, and I replaced it. There was a fair amount of corrosion, which I cleaned as best as possible. I then jumped it with my other jeep and took it for a drive.
5 minutes from the house I went to turn around and the car almost stalled. I revved back up and noticed that the "check gauges" light was on. The battery gauge was buried at 19. I immediately drove home, turned the car off, and the battery is dead.
So...never saw the battery gauge do that before. Am I looking at a fried battery? Bad connection? Alternator?
Any opinions would be greatly appreciated.