My Trailblazer had a similar situation. Had no-crank issue unbeknownst to me when I bought it. Happened so often I left a mechanics remote starter connected and lying up on the dashboard!! Puzzled me why it would start with the remote but not with the key. One day it so happened it wouldn't crank with the key and I had the time so I took a meter and started checking. Can't remember the specific connection but it was at the starter. A battery power cable...I had power on the cable eye. I had power on the hold down nut and it was tight and looked clean. I had power on the lockwasher. But when I metered the stud that battery power cable was connected to.....nothing! No power! I retested. Cable eye, yes. Nut, washer, yes. Stud, nothing. Well I'll be dipped in shit!! The remote worked because it was clamped to the stud!