In the vertical flight mode, thrust is provided by a lift fan in the middle of the aircraft and the aft nozzle which rotates 90 degrees down.
At touchdown, the lift fan had a malfunction, cause unknown, and now, all thrust is being provided by the aft nozzle, pointed straight down.
The pilot advanced the throttle to takeoff.
Since the lift fan is not producing lift, the aft nozzle thrust lifts the tail of the aircraft until the nose of the aircraft hits the ground.
The aircraft then tilts on its right wing and nose wheel & spins around.
At that point, it appears the pilot brings the power to idle, the plane reverses spin and returns to wings level.
The pilot then ejects.
It does appear that the pilot landed directly in front of the aircraft. Fortunately, the aircraft had stopped rolling.
My guess is that the lift fan malfunction was mechanical and not software (FADEC or fly-by-wire) related.
https://www.youtube.com/watch?v=VVyfGV0csD0
Watching it a few more times, it looks like there are a couple of puffs of white smoke that come out of the back of the aircraft just before the first touchdown. Remember, at this point the exhaust nozzle of the engine is pointed down, so any puffs of smoke are coming from inside the engine bay area.
Those couple of puffs of white smoke could be the beginnings of the driveshaft or clutch feeding power to the forward lift fan failing, and may be why the first touchdown was more of a bounce than it should have been.
Clearly, after the bounce, the aircraft noses in and is propped up on its side by the right main gear and right wingtip, with the engine nozzle pointing to the left, causing the counterclockwise spin.
As the main engine spooled down, the forward lift fan, still spinning through inertia, provided a brief clockwise spin.
Once both spins were neutralized, the aircraft settled on its main gear and the pilot decided to exit the scene of the accident.
Since it was still a Lockheed Martin aircraft (it wasn't yet delivered to the USMC,) we may never see the final accident report.