After delivering quite ado due to accidentall signing out from the DJI account, the screen of my remote controller is now blocked by the modal "Link Phone Number" prompt, offering to "Enter Mainland China telephone number". Since I do not posess a Mainland China telephone number, I tried to enter a Swiss phone number, with the country code. Unfortunately, the device is not satisfied with it and states that the number is invalid. How can one overcome it? Is there some specific format of entering phone numbers, which are not Mainland China ones?

It seems to be the same: https://forum.dji.com/thread-93158-1-1.html  and has been asked many times.
It looks as if the issue was caused by starting the flight simulator, after that the device decides it is in China (my DJI account properly specifies Switzerland), where the registration with the phone number might be required legally or something like that (no idea). In any way, my observation is the following: when the device is powered off after simulator usage and is powered on again - its functionality is blocked by a modal prompt to enter a phone number, which has to me a Mainland China one. I solved the issue (hopefully) by resetting the controller to factory settings with subsequent avoiding touching the simulator.

Please try to clean the cache data in APP first. Take the drone to outdoor place with good GPS signal and connect the drone and enable the internet, it will get rid of the phone link verification.

I have the same problem.
How do I "clean the cache data in APP first" as you suggest?In DJI Go 4, I can't do anything because it starts asking for the Chinese phonenumber.
I also looked in DJI Assistant 2 but didn't see any option.
Pls advice me.

fans5b2f68be Posted at 2017-9-7 23:13
I have the same problem.
How do I "clean the cache data in APP first" as you suggest?In DJI Go 4, I can't do anything because it starts asking for the Chinese phonenumber.
I also looked in DJI Assistant 2 but didn't see any option.

You can simply remove the APP from your phone, install it again, the cache data will be deleted, then try what Susan suggested.

I did find the solution already.
Did what you told us but without the "clean the cache data in APP first".
Problem solved!

fans5b2f68be Posted at 2017-9-7 23:13
I have the same problem.
How do I "clean the cache data in APP first" as you suggest?In DJI Go 4, I can't do anything because it starts asking for the Chinese phonenumber.
I also looked in DJI Assistant 2 but didn't see any option.

It really looks that you cannot do anything, but in fact, if you try to slide your touchscreen, you should come to some operating system controls and be able to get somewhere else. With my Phantom 4 Pro+  (no smartphone, built in Android-based device, like "a smartphone without functionality of a phone") I could get to the systems settings and reset the controller to the factory settings there, which solved the issue, supposedly caused by using the flight simulator, which seems to make the controller to believe it is in China. I even managed to find the way out of the "Give me a Chinese phone number" quickly, because I've already spent hours on figuring out "how to log in DJI account after logout, which for whatever reason, turns Wi-Fi off and the subsequent log in prompt seems to block the whole device while it is not possible to login due to missing internet connection" (same principle of sliding touchscreen to get some OS controls, which is not obvious for the beginners).

ahhhhh.....I looked, and you are a BEGINNER too lol    Don't be such a smartelec to people on here!

ALABAMA Posted at 2017-9-8 17:13
ahhhhh.....I looked, and you are a BEGINNER too lol    Don't be such a smartelec to people on here!

If it was addressed to me then yes, I am a beginner with drones trying to help to another beginner with the issue I've already experienced myself. Aside of being beginner with drones I have a degree in a related to electronics area and about 20 years of software development experience, which appears to be useful. BTW, I cannot get the point of your post - it does not seem to contain any information which might be useful for others. And, indeed, I used to another kind of correspondents, I will certainly not be missiing you on my site.

I was simply addressing your quote "It looks like you can't do anything" to
fans5b2f68be.  If I am mistaken then you have my sincerest apologies.

ALABAMA Posted at 2017-9-8 18:41
I was simply addressing your quote "It looks like you can't do anything" to
fans5b2f68be.  If I am mistaken then you have my sincerest apologies.

What's wrong with that sentence? This screen really looks to be blocking the device completely but in fact  sliding the touchscreen can bring out of there. Sorry for possible mistakes in En.

ALABAMA Posted at 2017-9-8 18:41
I was simply addressing your quote "It looks like you can't do anything" to
fans5b2f68be.  If I am mistaken then you have my sincerest apologies.

Got your point. Pardon, I am not perverse enough to get it immediately and could not suppose that the statement can be understood in such a way. OK, it should probably be "it looks that ONE cannot do anything".

fansb9972bfd Posted at 2017-9-8 18:52
What's wrong with that sentence? This screen really looks to be blocking the device completely but in fact  sliding the touchscreen can bring out of there. Sorry for possible mistakes in En.

Ok, I simply misread it.  My interpretation was not what you meant. Sorry again.

ALABAMA Posted at 2017-9-8 18:57
Ok, I simply misread it.  My interpretation was not what you meant. Sorry again.

I am sorry and apologize too.