Had the same / similar fault. I thought the PSU voltages looked OK as far as I could tell at the time, but fitted a replacement I had just to be sure. It had no effect, suggesting the problem with that set lay on the main board as suspected.
It seemed to me like possibly EEPROM corruption damage but before I got any further the client rang to say they had bought a new TV and would be collecting the old one.
Anyway, you can either try a reset of the 24LC256T in the usual way. If that does not work, if you have one, fit a new blank, and if that does not work, fit a new one preprogrammed such as CHS Part No 23008FW.
Hope this helps,
low.flying.pigs