Zgemma HS box showing no signal on hdmi


I have had my zgemma hs for over 2 years and tv working fine as normall. The other day my tv had only picture but no sound out of the blue. Tried everything from tv audio and video output settings and box setting, changed hdmi ports on tv still no luck and changed lead. Im not sure why its doing this as its worked straight for 2 years. My tv is a technika tv, but what I noticed is that when input source to hdmi 1 it automatically changes to DVI. Dont know what that is, did research and dvi does not give sound. Why is my tv suddenly changing to dvi?, also its not a fault with the tv because the ps4 and dvd players work fine as normal on the same hdmi cable