try the "upgrade" tab on the knc web control page.
Tried it, the thing sits there and does nothing.
I just get "Sending request to 192.168.1....." and it carrys on mining.
One die is totally dead and this one is not looking much better:
EDIT:
Dead one:
it takes time to upload the 17MB file. you need to stay on the upgrade page and wait. after upload, it will upgrade the system, and then get restarted automatically. during the process, do not switch to other tabs. or the upgrade will be terminated.
If after upgrading you still have die issues, you can power off the PSU and power on again. my neppy sometimes also has die issues. using web page to restart the miner does not work, but a hard restart solves the problem.