Just did a head job and now the truck wont start

98 Ford F-150
5.4L - V8
Automatic

The truck ran/started fine but now it wont turn over. I had the head gaskets
blow so i did a head/valve job done and re assembled the motor. But now i
got everything put together it wont start. The engine turned over while i was
putting the engine together, but now that the serpentine belt is on i cant get
it to turn over with the wrench like i did before.
The battery is fine. I even hooked up battery cables and tried to start it
when it was hooked up to my work van.
When i turn the key it does nothing. But if i hold it in the starting position it
will start to click. It doesnt click right away.
I replaced the battery cables
All the fuses are good
It started fine before i had to take the head off. So im thinking its something
I did, I just dont know where to start looking.