What you'll notice
Blocky artefacts, wrong colours, a shifted or scrambled picture across all sources — not just one HDMI input.
Why it happens
A failing video processing chip on the mainboard, or a connector between the mainboard and the panel working loose.
How we fix it
We isolate whether the fault follows the source (points to the mainboard) or is source-specific (points to that HDMI input), then repair the confirmed fault.
Still not working?
If the checks above haven't restored your mainboard (logic board), this usually needs a technician. Our TV Mainboard Repair service covers exactly this fault.