Hi All,
I've checked all forums on this site and on others, but I canot find the answer to the question I was wondering:

I booted up my Phantom 2 Vision+ for the first time in a while at my grandparent's beach cottage in West Dennis MA. It had a good compass calibration, gps lock, and flew pretty smoothly. after about 15 minutes I took her down and landed her on the beach, but before I could kill the motors she fell over causing sand to get stuck in the motor.

Later that day, I wanted to fly again, the battery was charged, along with the transmitter and remote. All looked fine until I heard sand inside the motors. I sat there for about an hour hitting it gently and all the sand came out. We even tried putting a vacum up to the motors to suck the sand out. We then turned on the motors and they ran smoothly, so we decided to fly. I took her outside, remembering not to be so ignorant as to let her tip over, and used a peice of plywood as a landing pad. I turned on the bird, the remote, the transmitter, and connected my iPod to the drone's network. I then tried to calibrate the compass. It wouldn't calibrate, and the lights flashed red to yellow and then back again.

I tried multiple stratergies, moving away from high voltage power lines, moving away from cars, keeping the remote at least 10 feet away from the controller, ect. No matter how hard I tried I couldn't get a compass calibration. We decided to call it a night, pack up the bird, go out for dinner at the Kreme and Kone (If you haven't been to West Dennis, It's an amazing seafood resturaunt) and drive home. We got home at about 10:30 that night.

Next Saturday, the day I'm writing this, we decided to try and boot up the drone. I went outside and saw If I could get a calibration, and I still couldn't. It was at this moment when I realized that I hadn't updated my firmware. I took the bird inside, plugged her into my laptop, and as soon as I connected to the NAZA software, and got an update. The update was sucessfull, so I turned off the bird and turned her back on. An error message popped up saying, "ERROR 27". In a nutshell, I found that there was a compass error. I used the forum to look for remedies for this problem, I used a magnet to circle around the compass, and noting worked.

If anyone knows how to help me, please don't be afraid to answer.
Thank you,
Vergique

Later that day - the first day - did the AC boot up normally?  

Mark The Droner Posted at 2017-5-27 13:38
Later that day - the first day - did the AC boot up normally?

Im having exact same proble.i tgink plug cane loose for compass

Mark The Droner Posted at 2017-5-27 13:38
Later that day - the first day - did the AC boot up normally?

Hi, Thank you for responding,
The AC did boot up normally and I could control the bird just fine. The only thing messed up is the compass.

fansb079625c Posted at 2017-5-27 20:46
Im having exact same proble.i tgink plug cane loose for compass

Thanks for responding,
If this is true, are there any ways to fix this? Even better, are there ways to do this without opening the bird? I am one faint of heart.{:4_117:}

If degaussing didn't work, I would agree with post 3 and check the connection next.  There is a connection at the compass itself and another on the center board.  Taking the top off is pretty easy if you have adequate drivers.  There's a GPS plug you'll need to disconnect after you remove the screws and the top is loose.  Lots of videos on youtube.  If that doesn't solve the problem, you can replace the compass - they're not expensive.  Good luck.

Mark The Droner Posted at 2017-5-28 05:10
If degaussing didn't work, I would agree with post 3 and check the connection next.  There is a connection at the compass itself and another on the center board.  Taking the top off is pretty easy if you have adequate drivers.  Lots of videos on youtube.  If that doesn't solve the problem, you can replace the compass - they're not expensive.  Good luck.

Thank you mark!

Just by coincidence a few mins ago I was recalibrating my IMU and there is a question mark on that screen of the Phantom Assistant software.  When I hover the pointer over the question mark, it discusses the ERR 27 which you mentioned above, saying degaussing the compass would make the error go away.  It says it would take several laps to properly degauss the compass.  So maybe you'd want to try that again.  

Mark The Droner Posted at 2017-5-28 13:14
Just by coincidence a few mins ago I was recalibrating my IMU and there is a question mark on that screen of the Phantom Assistant software.  When I hover the pointer over the question mark, it discusses the ERR 27 which you mentioned above, saying degaussing the compass would make the error go away.  It says it would take several laps to properly degauss the compass.  So maybe you'd want to try that again.

Hi Mark,
I took your advice and am happy to say that I got a compass calibration. I shouted with joy, packed up the drone, and went to the park dawn the street. I took out the bird, got another successful calibration, and took her to the skies. I was going to keep it safe, so I flew low for the time. I noticed throughout the flight that the bird wasn't very stable. I then took her up to about 50 and then it said "CRITICAL LOW BATTERY". I then began taking it down when it said "UNOFFICIAL BATTERY". I wanted to land it when it went into compass calibration mode and then I landed it. It was so unstable that when I landed it it was going about 5 mph in one direction before it could land. It really spooked me.
Thanks,
Vergique

Hi Vergique,

Just so you know, you don't need to calibrate compass before each flight.  You can go months between calibrations provided you don't travel far.

You must always launch on a fully charged battery.  No exceptions.  Did you?  If so, then it sounds like your battery is bad.  I would check the cell balance with Phantom 2 Asst and consider a deep discharge.  If that doesn't help, you will probably need a new battery.  I recommend a legit DJI battery.

The Unofficial Battery message is scary, I know, but nothing bad will happen from that message alone.  I get it with legit DJI batteries once in a while.  I don't know why.  The battery won't turn itself off or land the AC or anything like that from that message alone.  

I don't think it went into compass calibration mode during flight.  I've never heard of that happening to anybody ever.  Why do you think it did that?  

If the AC is unstable, an IMU calibration will likely fix it.  I would follow that with a compass calibration.  

Good luck!