Disconnect the HDMI from both the VM box and the TV. Turn off both pieces of equipment for a couple of minutes and then turn them back on. They should then perform a new handshake with each other.
Then on the V6 go to Help & Settings > Settings > Video Output > Video Output Format > Test Formats and follow the onscreen instructions.
Dave
The Service you do for others is the rent you pay for your room here on Earth - Muhammad Ali