Family Link - the device was locked, cannot be unlocked - what to do?

After posting an article about parental controls on Android on the Family Link app, it has been regularly reported in the comments that after using or even setting up Family Link, a child's phone ends up locked with the message that 'The device has been blocked because the account has been deleted without parental permission. In some cases a parental access code is requested, and in others (if I understand the messages correctly) not even that.

I tried to reproduce the problem on my "experimental" phones, but exactly the situation described in the comments I did not get, so please, very much: if someone can describe step by step what, in what order and on what phones (son, father ) was made before the issue appeared, please do so in the comments.

From most descriptions it follows 'account wipe', 'app wipe' and everything is locked, but which way, on which device - remains unclear (and I have tried both ways and means and still nothing is "completely" locked, the phone does not become a brick).

However, I give some possibilities for action, one of which may be useful:

• In https://goo.gl/aLvWG8 (opened in a browser from the parents account) you can ask a question to the Google family group helpdesk, in the Family Link comments in the Play Market they promise to help you by answering. I recommend specifying the child's account, which was locked, on the resource.
• If your child's phone asks for a parental access code, you can get it by going to https://families.google.com/families (even from your computer) with the parent's account, opening the menu in the corner upper left (it will have the option "Access code for parents"). Don't forget that you can also manage the family group on this site (in addition, by entering the child's Gmail account from a computer, you can accept an invitation to join the family group if the child's account has been deleted from there).
• If your child's age (under 13 years old) was specified when setting up the account, even after deleting it, you can restore it at https://families.google.com/ using the corresponding menu option.
• Please note the help to delete a child's account: https://support.google.com/families/answer/9182020?hl=ru. It says that in a situation where an account is set up for a child under the age of 13 and removed from their account without first deleting it on the child's own device, this can result in a crash (which is probably what is happening in the comments). Maybe the account reset that I talked about in the previous paragraph will work in this case.
• Also while experimenting tried to factory reset the phone through recovery (it will require entering the username and password of the account used before the reset, if you don't know them - great risk of getting a phone locked out of the way permanent) - in my case (with a 24 hour lock) it worked without a problem and I was given an unlocked phone. But it is not a method that I can recommend, since I do not rule out that your situation is different and the restart only makes it worse.

Also, judging from the feedback on the Family Link app, the app may malfunction and lock devices when one of them has the wrong time zone (if the date and time settings are changed, the automatic detection of time zone usually works fine). I do not exclude that the parent code is generated based on the date and time, and if they are different on the devices, the code may not work (but this is just my guess).

As new information becomes available, I will try to update the text and ways to unlock the phone.