Also best to be well clear of builds where gps multipathing may be experienced (gps signal bouncing off the wall giving inaccurate position)

I've updated OP with video upload from flight data.

You can see that there was little to NO controller input at most times.  You can see as the Mavic's altitude increased (during user input, or RTH), that it also appears to move NORTHEAST (towards true GPS location) although there were no forces in the horizontal direction.  You can see after RTH is triggered, and the Mavic heads towards the trees, the controller input shows I hit DOWN, but the it was unresponsive to this.

It also shows that RTH was triggered when battery was below 15%, although my settings show it should occur at 10%.  (Just nitpicking now).

Everything else I believe I have said over and over.
Yes- there was "user error" in terms of low battery on takeoff, not calibrating (although the settings said calibrations were "normal").  Also, I didn't validate the accuracy of the GPS before taking off, although the Mavic was extremely close (with 10-20M), it clearly was not close enough.

To continue to be a broken record and point out possible product issues:
**DJI should fix the notifications on the APP when flying Mavic and RTH occurs within 5-20M.  App states it will land, however this is inaccurate based on what occured, and what is shown in manual.  Also, simulator matches app, not reality of Mavic.

**RTH triggered at 15% instead of 10% which it was set to.

**Unresponsive RC inputs during RTH that would have helped avoid crash.

**Ability to takeoff in beginner mode without forcing calibration.

Strange things happen when you take off with drones with less than full battery.

If you had changed the RTH to 10% then there is something for DJI to check but i thought that the minimum was 10% for critical battery so the lowest you could go for RTH would be 15%, can someone check that as i don't have my Mavic to test. Fact is the moment you took off with 17% battery and a Home point that was not where the aircraft was you were doomed regardless of the APP or Calibration. Not being mean as i crashed my Mavic into a tree which was my fault as i broke my rule of not flying near trees.

Did you definitely do the firmware updates? As that requires at least 50% battery to update and surely the update doesn't deplete the battery to 17% or whatever it was when you took off?