How do I find the serial no of my mobile if it's locked? Samsung need this to unlock my account with them and I can only find the IMEI number on the box. It's an A20e phone and O2 say they can't unlock it because it's not an O2 phone.
Probably a question to ask Samsung, although I'm not entirely sure what you are trying to do?
Have you tried here https://myaccount.google.com/intro/find-your-phone?hl=en-GB
You can unlock your phone from there.
Or try this:
Track usage, upgrade and get support with the My O2 appDownload My O2