Do I have to do MCC unlock to downgrade or upgrade firmware on RM520N-GL

Hello dear friends!

One of my friends bought this modem and trying to change the firmware it seems that the Qflash just wont allow to do the upgrade/downgrade,

On the internet I have read that before doing it I we should unlock the device and I guess to do so we need to request a passcode from you for the model of modem we have, am I correct?

If it’s possible could you please tell me how to do it and were should I request the unlock?

Thanks in advance!!!

Dear @Tralula
Actually, we don’t lock modem when shipping it. Did it install in other device?
Please share what error is reported during upgrade.