Hi @jarwort ,
Try removing the batteries from the remote control and any other remote in the room as well and check if you can operate the TV normally using the TV controls only.
If you can then there may be a problem with the remote or another remote (if any), that may be causing the problem.
If still no good, disconnect the power from the TV, remove the back cover and disconnect the IR sensor board from the main board reconnect the power to the TV and use the TV controls to check if it works OK. Don't know the TV but it may be easier to disconnect the sensor board cable at the mainboard end
If it does it may be a faulty sensor board
I'm assuming this can be done as I cannot find a service manual for the TV but looking at the user manual the sensor is on the left side (looking at the front of the TV) and the controls are on the right (at the back or side?).
If still no good disconnect the power to the TV and reconnect the sensor board and disconnect the TV control board, reconnect the power and check using the remote.
The above suggestions are just to eliminate the controls as the cause.
If it is still no good after trying these then there may be a problem with the mainboard, as that is where the firmware that is used to operate the TV is stored.
Be safety aware when the back cover is removed from the TV and there's power connected to the TV as there is exposed lethal AC voltage on the power board. Always disconnect the power first before working in the back of the TV.