I have a 51cm screen (I think!), and similarly, I accidentally locked my TV.
I turn it on and it stays in standby mode, I press P+ or P- and the light turns green for about 10 seconds then goes back to red!
Yesterday, strangely, it restarted, a menu opened showing the lock programming mode. I didn't have time to unlock it before it shut off. And now I can't turn it back on!
And pressing P+ and P- at the same time doesn't work!
P.S.: I have an old TV model with a big box; I think they call it a cathode ray screen 'like for computers!
Any response???