Huawei+e303s1+firmware+update+free _verified_ -

: Never disconnect your modem or turn off your computer during a firmware flash, as this can "brick" (permanently damage) your device.

Note that updating the firmware does not always automatically unlock the SIM. You may still need an unlock code (Flash Code) to authorize the firmware write if the device is currently locked to a carrier. huawei+e303s1+firmware+update+free

Check here first, though they may have discontinued downloads for legacy 3G modems. : Never disconnect your modem or turn off