it auto shut off,

Same problem - lg OLED55B7V (6 years old) - it auto shut off, some times I can turn it on again and it works for a while and some times it just blinks at the stand by led but will not turn on. I have check all our remotes - they are all good, no power isues (do not have a amazone firestick). So i replaced the power board - this did not fix the problem..... :(