When I go to calibrate IMU, it stops at 1% and says 'unknown error occurred; recalibration required.' But, when I go to recalibrate it again gets stuck at 1% and displays the same message.

Yes, I crashed, into a tree, near the top, caught by branches. Took me a while to find it, and I had to climb up into the tree and even then use a long loose branch to reach up and slip the branch through the landing skid to get it. No outward appearance of damage. When powering up, the camera/gimbal does its normal routine, the camera works fine. Cables seem intact. But, something is wrong. Any suggestions?? Thanks. -Ken

The IMU may be stuck. I've seen that fixed but it involves breaking open the shell.

Thank you for that; I'll give it a try (need to get the proper tools first)

Kenwae Posted at 2016-12-26 15:10
Thank you for that; I'll give it a try (need to get the proper tools first)

Yes, make sure of that before you begin. Good luck.

Kenwae, sorry to hear about the crash, to ensure safety, it would be best to send it in for further evaluation.
You can submit a case here: https://repair.dji.com/en/SelfRepair/Area

I would like to thank Betamace for posting that video tutorial. I was able to fix the problem! It cost me $18 in tools, about an hour worth of time, and I learned something useful in terms of maintenance should this occur again.

Kenwae Posted at 2016-12-27 04:01
I would like to thank Betamace for posting that video tutorial. I was able to fix the problem! It cost me $18 in tools, about an hour worth of time, and I learned something useful in terms of maintenance should this occur again.

Yes indeed, I'm glad you were successful !

Still no problem?

Took it out and flew it a couple of times since the fix and all seems good. I tested the return to home feature, and it seemed to work right, it went up to about 3oo feet, where I set it, moved closer to landing area, but it started to come down and land maybe 20-30 feet from where it took off. I think that might be due to the proximity; that is, it wasn't really that far away from the take off point. When I first got it, the same thing happened. It was too close to take off point for return to home to be accurate enough. I'll test it again when it's a thousand feet away. I'm still rather incredulous that I was able to find the bird in the tree, and fix it! Thank you again for that tutorial....

Thanks for the update and thanks to Betamace for putting up that video it is going to come in useful for when I crash.

Kenwae Posted at 2016-12-29 03:26
Took it out and flew it a couple of times since the fix and all seems good. I tested the return to home feature, and it seemed to work right, it went up to about 3oo feet, where I set it, moved closer to landing area, but it started to come down and land maybe 20-30 feet from where it took off. I think that might be due to the proximity; that is, it wasn't really that far away from the take off point. When I first got it, the same thing happened. It was too close to take off point for return to home to be accurate enough. I'll test it again when it's a thousand feet away. I'm still rather incredulous that I was able to find the bird in the tree, and fix it! Thank you again for that tutorial....

Really, it depends on how many satellites are acquired. At first I was shocked when my typical RTH averaged 15-22 feet. I was accustomed to 18-24 inches from home point accuracy with my dual compass X380 but the whole idea is to have the drone come back close enough so you can regain control. Yet, 20-30 feet accuracy can land your drone up on a roof or into a tree if you allow it.   

Betamace Posted at 2016-12-28 10:43
Really, it depends on how many satellites are acquired. At first I was shocked when my typical RTH averaged 15-22 feet. I was accustomed to 18-24 inches from home point accuracy with my dual compass X380 but the whole idea is to have the drone come back close enough so you can regain control. Yet, 20-30 feet accuracy can land your drone up on a roof or into a tree if you allow it.

Yeah, and when I have used RTH, once I see it, I shift back to manual. When I have used RTH when the bird is way out there, it does come pretty much right overhead, and then I take control; it may well be number of satellites. But, that aside, it's flies great. In fact, it seems to boot up and ready to fly faster than before!