Herelink v1.1 airunit not working after update

i tried to upgrade the firmware of airunit v1.1 with connected to pc via usb and win flasher after update it blinks red led once and led is off after that. it is powerd via external 12v input. this happened in two of my air units.

May I know which LED was “blinks red led once and led is off”.
Can you please do the upgrade one more time and record it ?
Please make sure the 12v power supply , USB and antenna is connected while upgrade.

led 2 blinks red once after that no led is turning on i tried updating the airunit via pc but it shows no valid device and closes.