1992 LeSabre Computer Malfunction?

A couple of days ago, my moms 92 Lesabre Limited's battery died. She was jumped and everything was great, until this morning. The battery was again dead. This battery is new, not even 6 months old. I suspected the alternator, as we have had to take it back to Buick twice for replacements under the alternator's warrenty. To check it, I started the engine, and removed the negative battery cable. As I suspected, the engine stopped. I was told by Autozone that if the engine is running, and the alternator is bad, removing the negative battery cable would kill the engine. If it is good, the engine will still be able to run for a short while. Anyway, I reconnected everything and jumped it again. This time, I turned everything in the car on: the air conditioner, the high beam headlamps, the radio, and the rear defogger to see if the engine would die again. With the transaxle in Park, the engine stammered but ran. Then I put it in Drive with my foot on the brake. This is when all hell broke loose. The speedometer jumped from zero to 100, and the climate control panel turned every indicator on, reading an exterior temperature of 188 (which it was simply illuminating all of the indicators on that panel), and my ABS warning light came on. Then, the SIR warning light came on. Finally, the Service Engine Soon warning light came on. Then, the car shut off completely, interior lighting and all. Through all of this, the Voltage warning indicator never came on. I have not had the opportunity to check the ECU for trouble codes (doubt they are still in memory anyway). In all of my short time working on cars, I have never seen a simultanious, cascading system failure like this. Any ideas? Suggestions?

I know on my 88 Lesabre if you take off the neg cable even with new altenator the car wont run. I was told after all the years of how to check a bad alt is to remove the neg cable that on these cars you can remove the cable and the car wil not run so that theory was blown to bits. other than that I can not help sorry.

Alternator checked, not charging to specification. Alternator bearing failed. Replaced. Car now charging to specification. Computer monitored sensors are now functioning normally and there are no stored DTCs.

i have a problem i lost my key i try taking off the cilynder and start it but the security system activate...can i desactivated know that i found the key but the cylinder is broken?

i have a problem i lost my key i try taking off the cilynder and start it but the security system activate...can i desactivated know that i found the key but the cylinder is broken? its a lesabre 1992 [email protected]