Lg tv no sound or picture, blinking green light but back light on

suspect either a back light power board issue or main power board to back light board issue...also, is it under warranty ?

Fault at its main digital board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/
In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary.

Red light means your tv is in the stand-by mode..There could be serveral problems? Like your Y main board,T con,Upper & Lower buffer..Need to have a professional take a look ...

Hi,

Your power supply board is dead, u know basic electronics' and soldering? Most of the times, the power supply board just have dead leakages gases capacitors.These capacitors always bulges up on it top,or puff up on it top.Replaced these gases leakages capacitors will get your TV power stable,and work again.Or tries websites like Shopjimmy.com,Ebay.com to buy a whole refurbish power supply board for the replacement.
Hoping this work out in solving the problem.....

If the set goes dead after 3 times then suspect power supply, if a light stays on then main logic board.

When you say that you have replaced the main board i assume you mean the power board? If the green light comes on and blinks when the remote is touched it was never a issue with the mainboard, if it was you wouldnt have any signs of power. In most lcd tvs you have the main board which is normally the power board, the signal board which recieves signal and hold settings of the tv which can be all in one, the other is the inverter board, which scrambles the signal to what you see on the screen, and next we have the back light which lights the screen so you can see the picture, sometimes in certain models as i have learned you can have power/inverter boards which means the inverter and power are all on the same board, in your case i pressume the inverter board is seperate board and probably the issue you need to address, you can buy these online probably the same place you got your new mainboard from. Hope this helps pls post bach what happens.

Granger1212 we had the same problem. We called LG and although our LG was out of warranty by 4 months, we were asked to supply our proof of purchase and LG sent a serviceman to our home and in 2 days we had our television back working wonderfully. It's the power supply, call LG and BE NICE, I'm sure they will fix it.

Well dont keep it on!

By running it after it shutdown and it finally did its last pop that added another $XX to the parts bill.

The control boards (2) have now failed There are burned Capacitors ( pop!) and possibly even a few transistors burned out. This is not a DIY it is a Tech job as once changed these boards require additional tuning of the convergence factor.

seems to be common faults with this model in LG there have been a number of their models recalled to fix power board and the video controllers

Sounds like a overheating issue. Try facing a large fan blowing across the back of the unit and see if this changes anything. If it does, it might help to blow the back out with compressed air as dust might be helping it overheat.