That is an error code, which happens when the firmware is corrupted or a hardware defect (bad video board).
If no change, that points to a hardware fault, meaning a faulty main/control board, though there are many possible failure points. This issue could be a manufacturing defect, but is also often caused by a power event (shock/surge, prolonged over/under voltage condition, etc).
This could also be the result of age related wear and tear; as a 2006 model, that type of failure wouldn’t be surprising. This unit is well past its service life at this point.
There is one step you can take here, both as a possible fix, as well as a diagnostic evaluation:
1) Unplug the power cord from the outlet
2) Wait at least 1 hour (60+ Minutes)
3) Press and hold the power button (on the set, not the remote) for 60 seconds
4) Keep holding power button while plugging back in, and for another 60 seconds after. When plugging back in, go directly to the wall outlet, bypassing any power strips or surge protectors.
If this reset process does not work, it would unfortunately confirm an internal hardware failure.
This is something that would require repairs to correct; though repairs of these systems are not feasible, there are no parts available and repairs would cost more than replacement would. Your best recourse at this point would be to buy a new system. Should it come to that, I can recommend options for you.