Oppo A57 Mdm [verified] -

You can usually tell if your Oppo A57 is MDM-locked during the initial setup or via the system settings.

This is the only 100% legal and guaranteed method. If you bought the phone from a company liquidation sale or an individual, contact them. Ask them to: oppo a57 mdm

You need to confirm you are facing an MDM issue, not a software glitch. You can usually tell if your Oppo A57