I have a LG 55LF6100 was told to replace the t-con board an I did but still having same issue

The Tcon board is not working or there might be an issue with the back lights and the LCD and the screen for your TV.

Your LG has a problem on Main board controller. The main board has a graphics driver that give full cycle image going to t-con. Fixing this required main board replacement or repair. Look for a service technician.

You are right it's a T-com board issue. Replace it.

If all of the back lights are light up, the problem mostly is the display panel. we have seen a few of them.

T con board is responsible for the final image that appears on set. If there are anomalies or issues with it they can be traced to that board.

Please check the LED back lights strips, it is a common problem for your TV symptom.

Yes, when you power down the power, the back lights may flash on.

Sounds like the backlight has failed.

Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis. http://electronicshelponline.blogspot.com/ To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.

The t-con board controls the picture. To test it shine a flash light on the screen abd see if you can see an image when the TV is on. If you do then the T-con board is OK. Look at the back light ballast board (sometimes is part of the power supply board) If you see no movement or a dim picture with the flash light, then the T-con board is gone. You can get parts here: TV Parts Universal TV Stands DLP Chips ShopJimmy

This problem is most likely caused by the T-CON board. It could be a bad connection of the cable from the LCD to the T-CON board. or the T-CON board could be bad. Sometimes you can disconnect and reconnect the flat cable(s) to the T-CON board and solve the problem. Else you can replace the T-CON board.

The T-CON board is the board that drives the picture to the LCD screen.