First thing I would do is remove the props but keep any remaining blade pairs in their pairings, they are weight balanced.
Then, see if the drone, as it sits, will boot with out errors. If it does see if the motors will start, use the CSC to start them, if they start give the drone a bit of throttle and see if the motors rev, you will likely get a warning telling you to check the props. Stop the motors, if they are running, by holding the throttle closed. Pick the drone up and wobble it and check if the gimbal does its job. Check if the camera takes photos and video and saves them to the memory card.
If everything works then it might be worth doing a DIY repair but you will need to check the middle shell for damage around the rear arm pivots, the actual rear pivots can be ripped off the middle shell or rip the middle shell.
Replacing the middle shell means a complete dismantling of the drone and peeling ribbon cables off the shell, heat from the likes of a hair drier helps soften the double sided glue.
I doubt you will be able to get new GENUINE DJI parts so you will have to get ether second hand parts or pattern parts.
It's not too difficult if you have the tools and are 'handy'.
If you need to remove arms entirely you need a soldering iron, solder and perhaps a solder sucker.
If anything does not work then I'd suggest either a second hand drone or a sending the drone to DJI for at least an estimate, some of their 'repair' charges are very reasonable, you won't get your old drone back but should get either a new drone or a refurbished drone that is as good as new.