Hi, i've got the same HD+ STB for my secondary TV's which i got this month (April 2018) but the menu settings to get release number is not as given here (Menu -> help -> diagnostic -> system diagnostic -> release number ), for me its "Menu -> Settings -> Diagnostics -> Device Info" and my release number is 605.
I'm not sure why the STB shows a way older release number.
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Update: Called CC, they said release number varies on HEVC STB unlike Internet TV STB which has a same version across all devices. And that my version is the latest one and its impossible to update manually as it updates by itself when updates are available.