BC66 Firmware update not work

i can’t update firmware.

it is started but not ended or aborted. Can someone help me

For EC616/QCX212(BC260Y/BC660K) modules, upgrade firmware by main UART Port. Select Bootloader_xxx.bin from the firmware. Baudrate only config 921600;Then operate in the following order: trigger BOOT(pull down or short the BOOT pin) do not relax → click “Start” → trigger Reset(pull down or short the BOOT pin)→ release BOOT, then enter the download, until the upgrade is complete display “PASS”;