Batterie dies fast - 2001 Mitsubishi Diamante

Likely the battery is drained now if the engine died. But if the battery light was on a long time first, then I would suspect the alternator just died. However since you said it happened very fast, I would instead look for a short. Some melted wire where the insulation rubbed through.

Did the original battery die? Did you carry out any checks first like putting a meter across the battery to see if it was being charged? It should read 14.5v on a fast idle. Will it start when jumped with cables? Does the anti-theft need a reset procedure when the battery is changed? Have you checked the ground cable to engine connections for a good clean fit?

wont CRANK or CRANKS Fast but will not start , which is it?
the fuses blew or the battery is dead (discharged)
battery voltage is 12.6vdc rested, if not and is lower, its discharged.

did warning lights come on before the STALL? (died is stall)
if yes, and the charge lamp came on, and was ignored this is normal
for the battery to die. with alternator dead.

try jumper cable starts yet? that be next after fuses. and battery volts. (no cranking)
if it cranks fast, still fuses. check. then check for spark if not a diesel. some GV have Diesels, (3 kinds too)

Check the battery while the car is running. If the voltage isn't 14.3 or close the alternator is bad or going bad and not charging. Replace as needed.

The battery based off of its design and plate size can only supply so many amps. Even a battery that is reading 12 Volts could be in bad enough condition that it wouldn't provide the necessary cranking amps.

I would start;tune up,fuel filter, air filter,coils or cap and rotor.Check battery and connection.

if the battery dies that fast it may be time for a new battery.
have your existing battery load tested to see if it is any good.

This is easy to test but you need a multimeter. Connect the multimeter to the battery and run the engine at a fast idle (say 2000 rpm). You should get a voltage reading anywhere from 14 to 15 volts if the battery is fully charged and the alternator is working. If the reading is around 12 volts, then the alternator is not working.

Possible you have an earth wire loose ( contact wiring.) Loose battery terminals. Please start the checking from battery side and carefully not to cause any unexpected spark. That might cause a serious damage to ECU etc, My technical advise better a Car Electrician to do the job for your benefit.

I would check the alternator again, it apparently isn't charging the battery with engine running. You need a volt meter or amp meter to test this. Also does the battery discharge when the car is not running?