2005 gmc savanna 1500 starting problem changed starter and battery but when I hook up the battery charger and turn it to start boost it starts turn it off unhook charger it wont start

Check the battery like this:
Turn on the headlights, then try to start the car.
If the headlights do not dim or go out, then the battery is likely ok.
Check that the battery cable plus post, goes to the starter, Minus post to a good ground, like the engine.
If wiring is ok, then look at the starter solenoid for a good connection.
Problem is most likely the Solenoid or starting relay, whichever the car uses.
Hope this helps.

You have the solenoid exciter wire touch the bat terminal on the starter. You need to loosen the cable stud and turn and make sure it is not hitting the smaller terminal. the small wire should be going to the S post or terminal