EX6120 should now have power LED solid green and can be configured as normal

FWIW - On a Windows 11 PC, the following steps worked for me when trying to TFTP onto EX6120 which had a flashing power LED due to failed firmware update...

1 - Ensure latest EX6120 firmware (for example....EX6120-V1.0.0.72_1.0.43.chk file) is on the Windows PC.

2 - Configure PC with IPv4 address 192.168.1.10 (also 255.255.255.0 netmask, and 192.168.1.1 default gateway).

3 - Ensure TFTP is enabled on PC.....use the following guidance if needed...

https://www.thewindowsclub.com/enable-tftp-windows-10

4 - Connect PC to EX6120 using ethernet cable and ensure the EX6120 is powered on with the power LED flashing green.

5 - Run Windows PowerShell as "administrator".

6 - In the PowerShell window, ensure you are in the directory that has the .chk file, and then run the following command:

tftp -i 192.168.1.1 put .\EX6120-V1.0.0.72_1.0.43.chk 192.168.1.10

If successful, the command output should look something like the following:

PS C:\my_ex6120_directory> tftp -i 192.168.1.1 put .\EX6120-V1.0.0.72_1.0.43.chk 192.168.1.10

Transfer successful: 6283849 bytes in 27 second(s), 232735 bytes/s

PS C:\my_ex6120_directory>

EX6120 should now have power LED solid green and can be configured as normal.