security system

I recenly purchased a 1990 infinity q45, and when I changed the battery, the security alarm goes off, and I can't start the car. I have no transmitter, just a key. how do I reset the alarm? Help me please!!!

the alarm should turn off when you open the drivers door with the key. If no success, lock and unlock. Still no succvess, disconnect battery again, reconnect and re-try. Q45's are sensitive to low voltage conditions. The 90 did not have a 'remote' --only the titanium 3 pound key.