If it is still 8bit output then there is a new 444,10bit update available that also has a default 1000/0.005nits MaxFALL/MaxCLL
This will improve brightness of problematic mastered 4K HDR Bluray Rips:
Yeah copy the .tar into the .update folder and restart your device.
Or you can use a SFTP client, show hidden folders and do the same thing.
Can i do this by SSH command?
I´m saying activate 1000/0.005nits MaxFALL/MaxCLL by command via SSH