This is my first time posting and hope I can get some help.  I have owned my phantom 3 pro for about 3 months and have flown it about a dozen times.  Yesterday, I flew it at a Coastal Peak Park in Newport Beach California.  I had issues with the remote linking to the phantom and had to turn it on and off 3 times before it would establish a link.  Then I could not get the compass to calibrate, so I had to do it twice.  I actually turned if off again and turned it back on to calibrate the compass on the second try (turned it off, because I forgot where the compass calibration was in the app).  After that, I flew it at about 50ft high around the park and it was fine.  I them put into IOC course lock mode so I won't loose orientation as I am still learning on my phantom.  I took it up to 340 ft.  Then I rotated the phantom 3 pro slowly to get a 360 degree view.  Next thing I know, I get two error messages.  One stating Motor Obstructed.  One stating Motor Idling (loose or missing propeller).  I see my phantom spinning 360 non stop.  I am panicking at this point, as I think my phantom is going to come crashing down.  I proceeded to bring it down and now it is to the right of me, and I move it left.  I was able to land it, gentle in the park grass and it did not crash.  I check the propellers and it is not loose.  The motors spins freely with my hands with no issue.  I take it up to 3 feet, and it hovers fine and does not spin.  
     My question is what caused this and do I need to send it in for repairs.  Obviously I am paranoid at this point to take it up again.  My friends did tell me that there is a radio tower transmitter nearby and they could not get a cell phone reception to check their emails.  Could this have caused an interference to my phantom and caused it to behave like this.  It is currently running the firmware prior to the new update as I have not flew it for about 2 weeks.  As of two weeks ago, all of the firmware in the transmitter and phantom 3 pro was the latest firmware.  I did have live view on my phone the whole time I was flying the phantom and did not get any weak signal warning.  Also the flight log shows my flight of 6 minutes, but only a max alt. of 4.3ft, which is not accurate, because when I was flying it, it showed an alt. of 340ft.  The video is cache to my phone, so I know it was able to get the video.  Any help would be greatly appreciated.

make sure to do a complete level after avery update or when you first get it. do compass calibration as well as RC stick calibration after every update also. I would contact DJI and send them your flight logs and see what they say. If you do fly it again I would def advise removing the gimbal that way if it does crash it won't be damaged, and don't push it to 340 ft again. stay low and try different maneuvers. It could have been a total fluke and it might never happen again.

"Then I could not get the compass to calibrate, so I had to do it twice.  I actually turned if off again and turned it back on to calibrate the compass on the second try "

That sounds suspiciously like your problem or at least the mail part of it.
You don't need to calibrate the compass every flight.
ANd you tried to unnecessarily recalibrate in a bad area somewhere neear a lot of steel.
WIth a bad calibration, your Phantom started to rotate after you lifted off and got away from the magnetic influence of the steel where you calibrated.

A good compass calibration done in an open area away from any ferrous metal or electrical interference, and you should be good to fly anywhere, within a 200 mile radius...
It is definately a mistake to calibrate before every flight and if you do a poor calibration, it may cause a fly away or erratic flight situation.

I only recalibrate after the Go app or firmware has been updated. Also check all parameters in the app, incase the update had and will have reverted many of them back to their reset values.

RedHotPoker

When I did the second compass calibration, everything according to the phantom is fine.  I went through both stages, and got the solid green light, then the blinking green light, with the app showing compass calibrated.  From what the authorized dealer told me when I purchased the phantom, I was suppose to calibrate the compass before each flight if on a different day, or if I moved to a different location to fly it on the same day.  Since I have not flown it in two weeks, I did the compass calibration pre flight.  Even if the compass calibration was not correct, would it show my max alt. of 4.3ft on the flight log, when during the flight, the telemetry was showing it at 340ft?

chanf899 Posted at 2016-3-22 11:07
When I did the second compass calibration, everything according to the phantom is fine.  I went thro ...

No, that is a barometer error. It may perhaps be fixed if you do an IMU calibration. The compass calibration routine is stressed far too much. You do not have to do a compass calibration before you fly, in fact you can get away without doing one for months. The biggest risk in performing a calibration is that you get a bad one and it will affect the stability of your aircraft. I have not performed one since I got my aircraft 5 months ago.

Do it once, get it right and leave it alone. Nothing will change that will affect your compass operation unless you travel several hundred miles away from home, and even then, the change will be minimal.

So do you guys think all this has to do with interference in the compass calibration?  The video that was recorded on the SD card does show the barometric pressure go from zero to about 90 or 100 when I reviewed the footage last night.  So I believe the barometric sensor is working.  I have never done a IMU calibration.  Is that something I should be doing often or even part of pre-flight?

I guess the other question is can a bad compass calibration, even though I got the solid green light on the first stage and then the blinking green light on the second stage trigger a Motor Obstructed warning and another stating Motor Idling (loose or missing propeller)?

Sounds to me like a problem with the main circuit board. You need to download flight logs and post so DJI can look at them.

How do I get the flight logs and do I just post them here?

chanf899 Posted at 2016-3-21 21:09
So do you guys think all this has to do with interference in the compass calibration?  The video tha ...

you should do an IMU cal at least once when you get it.

after shipping around the world things gets banged up and out of wack etc.

Many times if you see a compass or interference alert on device simply move the quad to a new spot and it /they will go away.

as many say--set the compass correctly once  and forget about recalibrating all the time..

I had the same problem twice this morning. Any help?,please

Scary stuff that's for sure. I have flown in Newport Beach by Balboa Island with no difficulties. This forum is filled with some really smart people who can help you analyze what went wrong. My suggestion is to upload your log files so they  be analyzed by members of this group.

1-Go to http://www.phantomhelp.com/LogViewer/Upload/
2-Follow the directions, upload your flight record.
3-Cut and paste the URL from the address bar and post it here.

chanf899 Posted at 2016-3-22 15:10
How do I get the flight logs and do I just post them here?

1-Go to http://www.phantomhelp.com/LogViewer/Upload/
2-Follow the directions, upload your flight record.
3-Cut and paste the URL from the address bar and post it here.