Car not starting first time after stuck rear hatch

[Stevo96]

Car is a 2004 3.0. It's been working perfectly until yesterday. I went to pick up a really heavy long item that required us to lay back the front seat fully. I also jammed the item in which put pressure on the lower tail gate, on top of that my keys to the car got jammed in between the tailgate and the car body as I shut the tailgate without knowing they were there. This all could have nothing to do with it but seems odd that the issue arose straight after this.
When I go to start the car the lights come on the dash but the starter doesn't engage, it's as if the car is immobilised yet on the 3rd of 4th attempt it starts ok. Sometimes i can hear the tailgate unlock/lock itself...
Any ideas? I've tried disconnecting the battery for half hour but no change