For 90% of users, the ONT is owned by the Internet Service Provider (ISP). In this case, the best course of action is:
Until Huawei or its ISP partners adopt a transparent, public firmware repository (with clear versioning and signed releases), updating the EG8141A5 will remain an exclusive, clandestine art—a secret handshake for network rebels who refuse to accept that they don't truly own the hardware on their desk. huawei eg8141a5 firmware update exclusive
If your web interface is locked (grayed-out Update button), your ISP has disabled local updates. You will need to use the ONT's serial bootloader via TTL (Universal Asynchronous Receiver-Transmitter) or the Huawei V5 Upgrade Tool (a leaked utility used by field technicians). This is the exclusive method most forums won't tell you. For 90% of users, the ONT is owned