Mechanic Q: I just purchased a 1989 Jag XJ6 about a month ago. Finally?

I just purchased a 1989 Jag XJ6 about a month ago. Finally I was going to get the insurance and registration this week. I tried starting up the car last night and it was working just fine for a few minutes, then soon after the digital dash lights that show the battery power, etc. faded so I turned the car off and tried to restart it, and it wouldn't start back up. All the electrical power just seemed to disappear, such as the automatic seat belt and even turning the key in the door didnt lock or unlock all the doors. What could be the problem and what do you suggest I do to correct it? I would like to get this car on the road.

A: I just purchased a 1989 Jag XJ6 about a month ago. Finally?

Ok, so I have bought a new battery put it in and now the car is able to run, the problem with the key is fixed and all the outside lights work again, however, the problem with the digital dashboard is still unsolved. I cannot tell how much gas I have left, the temperature, oil, and even the mileage on the car is invisible. On top of that, the automatic seat belt is not working either. Are there any other solutions that you can give me?