new a850 no hdmi output

so far ive downloaded the firmware update A850_V1.02.06_2013_07_50 and installed it.
ive managed to tune it using telewest as the provider even though im in a ntl area

when i connect to the tv (lg 50 plasma) at best i get a flash of the screen about 1 out 10 seconds
i have tried the internet upgrade option but it tells me already upgraded

box info
c model
hv 1.0.00.00
sv1.02.06
jul 5 2013
h3.55

any help would be gratefully accepted

i have managed to get the 576p output to work but not able to get the 720 or 1080 to output :(