Catera not starting

Hey I have a 2001 cadillac catera and one night I went to go start the car and it would not even crank, it was silent. The next day I though it might be the starter so I took it out and got it checked, the shop said it works, also got the battery checked too and it was full charge. I can start the car with a screwdriver by touching the solenoid as long as the key is turned but without doing that it wont even crank. Cadillac dealer said its not the fuse but told me they have no clue unless I bring it in. I tried starting it with the key again and it started. I then turned it off and retried with the key and it would not start again. Does anyone have any ideas?