LGTV flashing box

[Sparks1010]

LG TV Flashing ! This Function Not Available Now. How do I factory reset? 42LN5200 LG tv has no control through remote or manual joystick. Only powers off when unplugging and automatically powers back on with warning box when plugging power source back in. Perfect picture behind flashing box when connected to any source eg. directv, ps4, blueray player. I have tried all the usual reset protocol and now have back cover taken off with boards exposed. Tried disconnecting and reconnecting all connectors

 

[Ralston18]

From LG:

Disconnect the TV from power, then press and hold the power button on the TV itself (not the remote), for 10 seconds (again this drains residual current and can effectively reset in many cases), and release. Then plug the set back in, and press power once. Then let me know if you can get the LG logo on the screen, and/or if the remote has any functionality.

Source:

http://www.justanswer.com/tv-repair/8gg2y-help-lg-42ln5200-tv-screen-blue-don-t-know.html