TV shuts down when connected to something

Hello everyone. My Chimei TL-55ZX800D (sorry, the model is absent in the devices) shuts down when connected via HDMI/VGA to PC/ any other device. The screen is projected for 1 sec, then it shuts down. It works if it is warmed up for ~15-30 min. It started a few weeks ago, after we started to connect PC to TV without turning them both OFF first. I checked the capacitors on the powerboard, but they seem to be fine. What else shall I replace?