Dropbox login problem on PocketBook

[DUUD]

I ran into problem with login on PocketBook integration. 
Once I try to enter the account (I type login and password correctly) and press log in the small circle starts rotating near the login button. After 5 seconds it disappears and nothing happens.
How can I solve this problem?

(Model№PB740-2, all the fimmware updated)

[Mark]

As its a third party tool you need to speak to Pocketbook I'm afraid

[DUUD · Accepted solution]

Here is what PocketBook support asked me to do and it helped:

"

To solve the problem, we recommend you to perform the factory reset by choosing "Settings - Maintenance - Factory Reset". 

Please note, that all notes and bookmarks will be deleted.

Also, please, specify the serial number of your device, Settings - About device - Device model - Serial number.

Check whether the device functions properly afterwards and kindly inform us the result.

Best regards,

Customer Support Team

"

I am posting this information here to help others with the same problem.