Mike, you login to Blitzortung Org, not the forum, to the operator's page. Under project info tab, select "compendium"... you'll see a list or info... see 'firmware', and make sure you select the correct firmware for your system... don't install a 'Blue' Update, on a Red system, and vice versa....
Download the correct firmware version to your computer.
In your System GUI go to 'tools' and follow the instructions for "System" "firmware"
It's possible on a 'major' firmware 'jump', from a very old version, that you'll have to do a cold system restrt... remove power, etc...
but also give the system time to reset itself.
Again the firmware is NOT public.
Mike