Unplug all HDMI cables and then the power plug from the TV, wait 10 minutes and then put the power back into the set, (don't power up yet) and add one HDMI cable to a source.
As to your lawsuit, if you tell support that they note it's not a support issue but a legal department one. You might explode as support won't take your calls.
There's another issue and it's been beat around for years. The warranty is only so long but you have a lot of folk using the "it should last longer" angle. They usually flame on.
two days ago i was using the LG TV with the HDMI ports and everything was fine most of the day. i have my computer and my Onkyo Receiver attached to HDMI ports on the TV. the whole system is connected with power using an APC UPS battery backup so I know there is clean power and no electrical spikes in my system setup. I shut my PC down and decided to use it again. I select the Input selection on the TV and the connected device is detected because it is not grayed out, but a few moments later a "no signal" message started bouncing around on the screen with the LG logo. i tried connecting the HDMI to 4 ports on the TV but still have "no signal" message. i tried connecting my VGA display port from my computer to my LG LED TV's VGA port and that too gives me a "no signal" message. I use rabbit ear antenna for over the air TV broadcasts and that still works fine. when i select the NetCast button on remote control that starts normally and i can still watch Netflix using the Ethernet connection. the RED-WHITE-YELLOW composite RCA connection still works when device is connected. I called LG support and they kept telling me the TV is out of warranty so there is nothing they can do for me. I received my LG TV January 2011 and was listed as being a $2,800 television, i got it on sale for $1,300. after only four years of use this should not be happening considering the amount of money i paid for it. I found allot of users in my online searches having the same issue with "no signal" being displayed with their HDMI ports. LG needs to step up and address this issue. if they do not all I can think of is a "Class Action Lawsuit" needs to be brought against LG for this issue. the issue for me started August 17, 2015.