OP I'm sorry for your loss, really. It is stomach wrenching when it takes off on it's own mission and you just stand there helpless.
However -
Good luck with getting anything from DJI - and even better luck with your credit card company. Unless you can prove that the goods were faulty, they won't entertain you. Don't ask me how I know this (previous experience!). I've had phantoms for over two years, had two fly away and ditch in water, and both times the evidence pointed to (1) pilot error in the case of my P1; and (2) external magnetic interference in the case of my V+. DJI didn't respond to either incident, and CC company (Nationwide) just about told me to feck off.
If I was you, I'd take the earlier advice and go and search around the area ringed and see if you can salvage what's left of your aircraft. From the clips posted, esp the second video clip, where the aircraft looks to be flying away sideways, I would conclude that something affected the compass. Maybe not your fault, but I'd wager that DJI would say that it wasn't their fault either, if you can get them to reply to you.
Sorry if this all sounds harsh, but after four phantoms, three flyaways (one recovery!) three rescues from trees and countless heart-in-the-mouth incidents you just become numb to reports of flyaways.