If you brick the device, use the "Force Download Mode" method (shorting pin 1 and 2 of the flash chip) – a topic for another advanced guide.

Finding free, official firmware links can be difficult as Huawei does not host them publicly for consumers.

offer various service and technological firmwares for the E303s-1, including tools for recovery and IMEI restoration. Huawei Enterprise Support

In 2015, a budget traveler named Marco picked up a second-hand Huawei E303s1 USB modem in a Bangkok market. It worked fine for a year, then started overheating and dropping connections. A local tech forum mentioned a firmware update could fix it—but official links were dead, and Huawei’s support page for that legacy model had been quietly archived.

Do not download firmware from torrent sites or unknown blogs without file hashes (MD5/SHA1). Corrupted firmware can brick your dongle permanently.

Simply plugging the modem in is sometimes not enough for a flash. The modem must be in a state ready to accept files.