Just a quick update:
Ultimately, I went through FIVE replacement Mavic Pro aircraft, two refurbished (returned immediately), and three new aircraft.
One of the refurbs I returned without flying it. When it got back to DJI, for some reason it went to their repair line, where they found the problem I was having (I didn't fly it, remember!), and replaced the defective gimbal controller board! This, of course, begs the question, "Why wasn't the problem with the gimbal controller board found during the refurbishment procedure?" A clear example of why you should never accept a refurbished aircraft in exchange for your new aircraft... You just don't know whether the refurbished aircraft was ever truly fixed, or just cleaned up and shipped out to a new owner.
A supervisor at DJI said he'd take a new aircraft off the shelf, unbox it, do a full physical and electronic quality control check, then have his flight team test fly it, and record video (leaving the video on the SD card). He said he'd analyze the video on his computer to make sure everything was 100% working. I sent Mavic Pro #4 back to him, and 2 hours after it was dropped offof at UPS, he shipped my new Mavic Pro to me. When I got it, I found the following:
- No flight records on the Mavic Pro aircraft
- Firmware was updated, but there was a firmware mismatch between the battery and the aircraft
- Battery had never been charged
- Packing materials still in place on the gimbal, back of fuselage, camera lens and covering the Forward Collision Avoidance sensors
- No video footage on the SD card
Clearly, the supervisor has done none of the things he promised to do.
I updated the firmware (it arrived with 4.01.0200- on it... I assume the "-" implies beta firmware?) to make everything consistent, charged the battery, and did some test fights. Result... Same issues as before.
I wrote email to the supervisor detailing my findings, above, and asked exactly what tests were conducted on it prior to shipping, and where the video was. My email was ignored!
A week or so later, I received an email from someone new at DJI. The email said that based on my description of the problem (they clearly had not read the entire email thread, or the ticket information, or looked at the flight logs, or the DAT files, or watched the videos I sent them)... my Mavic Pro was "behaving normally"!!
I've kept that Mavic Pro. The problems with it, while still present, are less pronounced than any of the other replacements I'd received, and it is a new aircraft, not refurbished. I've updated the firmware on everything,,, aircraft, batteries, controller, and the DJI Go 4 app... all to the latest versions (firmware 4.01.0200 was replaced after only 10 days, so something must have been really bad with it!). The latest firmware and software versions seem to have reduced the problems a little more, though they are still present. DJI is basically ignoring me now.
I later found threads on the DJI forums that describe the exact same problems that I am experiencing. One thread has been active since February 2017, with just one comment from DJI! All in all, I found something like 7 threads all describing the same problems, none of them with any solutions from DJI. With the introduction of the Mavic Air, there have been several new threads started where problems with rotation of the Mavic Air during hovering and drifting to the right when flying "straight" has been described.
And so the saga continues.