Cadillac Repair: 1984 Cadillac Eldorado, cadillac eldorado, altenator

Question
Good morning.....I recently had a mechanic "replace" the computer in my '84 Eldorado because it wouldn't start.  This is what he said the problem was after he put it on the diagnostic computer.  After the computer problem was supposedly fixed, I took the car to get the catalytic converter "gutted".  It is now 2 weeks later and the car won't start again.  I don't think it's the battery or the altenator.  Do you have an idea of what this problem could be.  I don't have a regular mechanic to be able to stop by to take a look at it.  Thanks for you time.....  

Answer
Perform this test:

1. Locate the OFF and WARMER buttons on your climate control panel.

2. Turn ignition ON, Engine OFF.

3. Simultaneously push and hold the OFF and WARMER buttons for 2 seconds and release them.

4. Write down every letter/number code that appears until it stops displaying numbers and you see .7.0

5. Turn OFF ignition.

6. let me know what you wrote down .