Unlocking via a simple code isn't always possible on newer firmware versions (often referred to as "New Algo"). In these cases, is the only reliable method. Using verified firmware is critical because:
Prevents "bricking" (rendering the device useless). huawei e8231s1 unlock firmware verified
This usually happens if the modem is still being used by another program. Close all dashboards and try again. Unlocking via a simple code isn't always possible