Mitsubishi Repair: 95 eclipse gsx, eclipse gsx, dash lights

Question
hello. im considering purchasing a 95 eclipse gsx. just 2 days ago, the car was running great. i started it up, ran smooth. then the following day, he said it died on him, he thought the alternator went out. he said the lights were dimming down, and when he came to a stop light, or slowed down dramatically, it tried to die on him. he said that you could jump the car off, and it would run fine if you gave it gas. i went to look at it today. i hooked my multi-meter up to the battery, and the voltage was extremely low. i tried jumping the car off from my vehicle, but it wouldnt turn over. the headlights, dash lights, etc all came on. but then, the turn signals and the dash lights were flashing, along with a beeping noise like something from an alarm system. i disconnected his battery, and ran my cables directly to his, but same thing. im thinking i should try putting my battery directly on the car, and run a ground from the negative terminal directly to the block to make sure its grounded and the battery has good connection. whats your opinion? thanks, caleb.

Answer
Caleb,
If the battery falls below a certain voltage, the car alarm/anti-theft system can engage.  Until that is disarmed, the car will not start.  It sounds as if the real problem is why the battery got drained so much in the first place.  It may be caused by a bad alternator or improper ground in the charging system.  Either way, you'll want the the current owner to fix all of these problems before you consider yourself to be the new owner.
Good luck!