Why is my flightforce stunt drone back part tilting and wont lift off?

Recently, I received a Brookstone Flight Force Stunt Drone BD20. I was playing with relative and he crashed the drone in a door. The drone is now tilting when trying to take off and it does not take off normally anymore, its two back blades (or back legs) dont take off but the front ones do. We tried calibrating the drone but its the same. pls pls help. I aso tried changing its blades but its the same. Please help. I also tried changing dame but its the same.