This is a “soft brick.” Try:
After updating, check that the firmware version has changed: download zte mf927u firmware upd
Use this if OTA fails or you have a local firmware file. This is a “soft brick
: Use a USB connection to interact with the device. The tool should detect the device as "ZTEMODEM" or a specific COM port (Port 80). Flash Logic Place the device in Debug/Fast Boot Upload the firmware file. download zte mf927u firmware upd
Download and install at your own risk. If you want, tell me which region/carrier your MF927U is from and I’ll look for the correct official firmware link.