Hi Ashiqur,
I really understand your situation. We are willing to assist you, but the forum support is different from the on-site support. We need to collect more important information via the forum, and then offer you some useful advice. Thanks for your patience and cooperation.
To check the UPN on the Office 365 side, I have mentioned in the previous post. You can login to Office 365 Portal > Users > Active Users > Select a user, and then click "EDIT" > Details > User name.
To run "Set-FullPasswordSync", please go to the Dirsync Server > Start Menu > All program > Accessories > Windows PowerShell > Right click "Windows PowerShell", and then click "Run as Administrator" > Run "Import-Module DirSync" > Run "Set-FullPasswordSync".
Thanks,
Edward Qu