changing battery alarm going off lock out feature kicks in on 1996 Buick Roadmaster

my battery died and i got a new battery changed the bolts and terminals but it still goes to lock out feature and car alarm goes off won't let car crank

2 answers
If this alarm is after market you have to turn the toggle switch off first .This sounds like its not factory installed.
took me forever for some one to answer this and $20 all u have to do is put the key in the ignition and turn it on then connect the battery