you may have to use the scart cable in order to access the box settings and then change them to HDMi, before the HDMi port will work. I recall an engineer needing to do that when ours was installed ages ago. ( & he'd struggle to do that nowadays as many new TVs no longer even have a scart input )
SCART is obsolete analogue rubbish by moderen standards - only HDMi can give you a HD picture
