2002 Tahoe starts and then dies

[86k10]

I'm working on an 02 for a friend of mine and he said after replacing the battery it started doing this. The only code I find is a 1626. I put a new GM ignition switch in it and nothing changed. The security light also stays on even when the key is removed. Also the automatic head lamps dont come on when you turn the key on but you can turn them on manually. The dome lights dont work and neither does the remote. Has anyone ever experienced this? I have read a lot and watched a lot of things but nothing covers what issues I am having.