This usually indicates an incompatible file version. Double-check that the firmware file specifically lists the sub-model, as firmware for the B311s-220 or B311-223 will fail validation. Share public link
A progress bar appeared. The lights on the front of the B311-221 began to blink in a rhythmic pattern he hadn't seen before. The status bar on the screen warned: "Device is updating. Do not power off." Huawei B311-221 Firmware
The Ultimate Guide to Huawei B311-221 Firmware: Updates, Installation, and Troubleshooting This usually indicates an incompatible file version
If an update is interrupted, the router may get stuck in a boot loop or show only the power LED. Huawei B311-221 Firmware
Ensure your power source is stable. Powering off the router midway through a firmware write will permanently damage the system motherboard.