Hi, I have a problem that M100 fly away (When M100 takes off, M100 cannot hover and draw a circle too fast!!)
DJI says to me that this is the problem that you controlled the M100 at a magnetic interference place.

Therefore, I want to check whether this place is magnetic interference place or not. (Hopefully, I want to check the magnetic interference degree)

I think M100 flight place is not magnetic interference place.

please help me~~ thank you.

Just to clarify, do you have Guidance installed on your rig? Was all the firmware up to date? Is the GPS/Compass puck installed properly? Do you use SDK?

If your mag is not calibrated right you see a toiletbowl when hovering. If the mag is completly off your copter may not even hover right.
Go to an open area where no iron parts (cars ect) are around. I usually take off belt, watch, glasses, phone ect. Then calibrate the mag. Given that you mounted the mag/gps right, the heading should be fine now. Check it in the go app. Compare the heading to a compass (phone). You should see a similar value on both mags.     

Cheers
Christof