Panasonic TC-P50ST50 Plasma won't turn on

Was watching on my Panasonic TC-P50ST50 plasma TV when it suddenly turned off. Tried turning it back on and it froze at the "Viera" logo startup screen, and it would not turn off with the remote. Tried unplugging it and replugging it; now it doesn't turn on at all. The red light will turn on when plugged in, and after dormant for a while the remote power button will turn the red light on again. But nothing appears on the screen, I can't bring up any menus with the remote, and neither the remote nor the TV power button will turn off the red light. I tried unplugged 60 secs holding TV power button, plugged in 20 secs holding TV power button, 30 secs plugged in holding TV power and a volume button, and 30 secs plugged in holding TV power and remote power buttons. I heard a click with some of those, but otherwise they didn't change the situation at all. Any suggestions or is it finally dead (been 12+ years now)?