I just replaced the heater core on a 98 Pontiac grand prix super charger and now

I did the work myself. I had no clue what I was doing but had a manual (Chilton) and put everything back in the reverse order as I had taken it out. It does have the theftlock radio that I didn't know was supposed to be disconnected before working under the dashboard could this be the reason? Thanks for your input.

If the radio is the problem, it wouldn't work without a code being entered. If it wasn't ticking before the repair, then something was missed or it wouldn't be ticking.