Can you give the model of the TV?
Also is the red power light blinking steady or is there a pattern to it? (For example - blinks 4 times, waits a second then 4 times again, etc..)
This error code indicates a problem on the main board to do with digital input processing.
Switch the set off, unplug from wall and unplug all input cables and repower, if the set now starts then plug the inputs in one by one to find the bad input. You can then use the TV by bypassing that input or call a service technician for repair of the bad input.
If the set still doesn't start with all inputs out then the set will need a serviceman I'm afraid.
If you are comfortable with electronics repair, you can remove the back of the TV and check if the D935 on main pcb (with tuner) is seated properly.
Lastly - If you are attempting repair yourself, I always check the capacitors on the main power board. They are a common source of failure and can contribute to the other problems.
Unfortunately, if you aren't familiar with TV internal components... yes.