car sat few months battery died replaced battery. now will not crank

having same problem with 92, immobilizer is an led flashing ? what sometimes works is remove neg battery terminal and wait 15 mins or so then re connect or under glove box behind the panel is a wire harness connector that can be unplugged again for 15 or so and light nay stop wont turn over till light stops. UPDATE # DAYS LATER ! I got my immobilizer to turn off finally. here's how - I turned the key to the on position witch activated the system 4-ways led flashing fast etc. then I disconnected neg. cable from battery waited 15 min then put cable back on with key still in and on .it worked the led went out and i can start the car again.