1996 plymouth grand voyager?

i took out the computer to try and see if it worked on my other 1996 grand voyager and it did, but then i put it back on the original van and it wont turn on! the computer is fine theres some kind of security thing that wont let me turn it on. it has no alarm but it came with a factory installed alarm that has been disabled for the past 10 years! i can only turn it on if i spray starting fluid through the air intake! i found out that the fuel injectors arent spraying any fuel, all the fuses are good, any ideas?