2000 Alero not starting

Recently had BCM issues, a lot of corrosion in it, so I bought a new one connected it, let the key stay in the ON position for 15 minutes for it to relearn. It had been running beautifully until today. I go to start the car and it starts up then shuts off right away. Well at this time I'm in a parking lot with no where to go so I sit there and try the relearn thing again, didnt work. I happened to still have some electrical cleaner in the car so I sprayed out the key hole and key, removing all the junk I could. Nothing. I unplug battery and reconnect BCM. Boom starts up. Drive it home and go back out a couple hours later to start it again. Does the same damn thing, starts up and dies. Security system light is on so I do the relearn again, nothing. Unplug the battery only this time and it starts fine, but dies on second try. Do I get a new ignition switch? Every time I unhook battery it starts up first try but nothing after that. Security system is over riding everything. I don't want to sink too much money in to this car seeing as it has 222k miles, time for a new one, just not quite ready yet.

Any help would be greatly appreciated.
Thanks

Think you have a Passlock problem......if you scan for "B" codes, you will probably find a B2958 or B2960......usual fix is the Passlock sensor.....

This MAY sound a bit elementary, but make sure none of your fuses are blown.