How to bypass or reset my security system

What is your question?

I replace my whole dash and unplug my security system well when I put the new one in and plug it back in now my truck will run for a couple of seconds and then die and it was running perfectly fine before I took the dash off and the security light will come on flash for 3 seconds and then go off

What makes this problem better or worse?

Nothing

How long has your 1998 Chevrolet K1500 had this problem?

A few weeks