If all external factors have been exhausted, checked and ruled out, then the described symptom would confirm the internal hardware issue. More particularly, potential suspects after a review of the Service Manual are:
- • failing panel/screen (least likely);
- • about to fail main/BU board (likely);
- • faulty T-CON board (most likely).
The T-CON board P/Ns 55.46T02.C02, T400HW01 V3, 40T02-C04 of this particular model has a known high failure rate. This board is not that readily available. However, there are offers for the repair/refurbishing of this board. Please click HERE.
Not that often a cause of failure but still possible would be the main board. Subject to confirmation from the current/existing BU board, it would have a printed number of something like A-1643-239-A (1-876-561-13) similar to the part offered HERE.
It has to be posted that the board numbers may be different subject to manufacturing revision and updates hence the need to order a replacement board with completely identical numbers.
Component level repair or replacing the board would serve as an attempt of a fix and as a test by process of elimination.
If not corrective, then the panel P/N 1-802-639-13 would be highly suspect. If so, repairs may no longer be economically reasonable.