Hey,
i had crash today with my phantom 4. Propelers are all broke, but rest of drone look fine (some scratches). What should i do to diagnose that for sure rest of drone work fine? Step by step what should I check.

1) Take off  the broken propellers and check the motor tops to see if anything is broken off there, should be 3 posts on each.
2) Check free movement on each motor's rotation
3) Check that the motors are all straight
4) Calibrate IMU's
5) Calibrate Compass
6) Calibrate Gimbal
7) Calibrate vision cameras (need DJI Assistant app and PC)
8) Check fit of battery in battery compartment

If anything is wrong with the flight systems the drone will tell you during calibration.
Keep your first flight after a crash short and close, until you are sure its flying ok.