ECU probleM?HelP

WHats up....so as some you you know i have a 96 gsr ls/vtec. Couple of days ago i got the alternator changed cause the it was gone. Car was running strong for 2 days. Than it seemed like it was the alternator again cause the battery was brand new anyhow took it to my mechanic he said evrything was gfine but thet it might be wires running from alternator to ecu. Or something is shorting out. ALL wires were checked and fine so hes telling me its the ecu giving me problem. BTW it was a ecu from a junkyard. So NOW my question is if i get an ecu that is compatible with my car can i just disconnect plugs from old ECU and plug them into the new ecu? And would everything be working properly? Would i have to do anyting special to the new ECU? And what ECUs would fit in my car 1996 gsr obd2. ANy help is appreiciated sorry for the long post but i NEED help!am new to hondas so be nice!

I wouldn't just jump to conclusions about the ECU.

Put a 12 volt test light in line between the battery cable and positive terminal. As long as the 12 volt light is illuminated, you have a draw. Start pulling and reinstalling fuses, one at a time, until you see it dim or go out. If it goes out, you found your draw. If it dims, slight draw, such as radio memory etc. if all else fails, make sure you know where they all go, then pull them all, and start putting back one at a time. When light comes on bright, you found the circuit causing the draw.

Sometimes batteries are just defective. I'd rather replace a cheap batter first, then buy an ECU if that's not the problem. The alternator is responsible for recharging a battery.

What are the symptoms of the car anyways? Does it turn over fine? Sputter after awhile? At night do you notice interior lights are really dim? If so then your alternator is still malfunctioning.

NO you see thats the thing car runs fine strong and no loss of eletrical power ust doesnt turn sometimes and battery dies i got a new batt so i know its not that when tested with voltmeter it read below 12 volts which i why it doesnt crank the alternator charged the bettery and kept the charge but it wuld basically not turn on wheneve it wanted so it was something else esides the alternator or batt the mechanic said ,

test the alternator and check for parasitic draws as previously stated