Flickering and focusing in/out picture including some sound spikes and red LED light flashing

What is the model number? If it is only 3 years old, I suspect you have a LCD TV with LED backlight. You quite possibly have a failed LED backlight.

Many LG TVs of this age are starting to fail due to over-worked LEDs in the backlight which create the white light that illuminates the LCD image.

The symptom is TV turns on and off ok, gets sound on the connected video inputs, but has an otherwise black screen with no video on display. You can try to operate the TV near a bright window with lots of sunlight and see if you can perceive a faint image on the screen. A flashlight is often not bright enough to be helpful.

Most of the time, an LED will fail as a short circuit and still allow power to flow through it to other LEDs that will still light up. If one of these LEDs fails as an "open circuit", or if several LEDs have failed in the same circuit, then the power supply detects a fault and shuts the TV down. If the LED is intermittent, you may have flickering. Think of having one light bulb burn out in a string of Christmas lights and having all the lights go out until the bad bulb is replaced... kind of the same thing.

Your TV circuits boards should be fine. In my opinion your TV requires a backlight repair which requires complete disassembly of the entire TV including disassembly of the panel which is a difficult process.

whats the exact model? are you getting a red light on the led lights on the on button? flashing or solid red? check all the connection make sure all are tightly connected from the back of your television

Back - light problem. 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.

If your LCD TV or monitor has stopped working, or is displaying one of the following symptoms, then it's a candidate for some new capacitors
- Flickering screen
- Screen image disappears after several seconds
- Dim screen
- Slow start
- Power LED on, but no picture
- Unusual colors and/or lines
The primary cause of LCD TV and monitor failure is caused by faulty capacitors. You can examine the capacitors in your LCD TV or monitor and actually see if they are bad.
If they appear bulged on top, then they need to be replaced.
New capacitors will solve a host of problems in LCD monitors and TV's and will extend the life of your monitor or TV by several years.
Check the cables, connectors and connections.
Take it to a repair shop.
https://www.youtube.com/watch?v=TR2iWN6b-LY
LCD TV Repair No Power Power Supply Common Symptoms Solutions How to...

If your LCD TV or monitor has stopped working, or is displaying one of the following
symptoms, then it's a candidate for some new capacitors
- Flickering screen
- Screen image disappears after several seconds
- Dim screen
- Slow start
- Power LED on, but no picture
- Unusual colors and/or lines
The primary cause of LCD TV and monitor failure is caused by faulty capacitors. You can
examine the capacitors in your LCD TV or monitor and actually see if they are bad.
If they appear bulged on top, then they need to be replaced.
New capacitors will solve a host of problems in LCD monitors and TV's and will extend the life
of your monitor or TV by several years.
Check the cables, connectors and connections.
Take it to a repair shop.
https://www.youtube.com/watch?v=TR2iWN6b-LY
LCD TV Repair No Power Power Supply Common Symptoms Solutions How to...

If your LCD TV or monitor has stopped working, or is displaying one of the following symptoms, then it's a candidate for some new capacitors
- Flickering screen
- Screen image disappears after several seconds
- Dim screen
- Slow start
- Power LED on, but no picture
- Unusual colors and/or lines
The primary cause of LCD TV and monitor failure is caused by faulty capacitors. You can examine the capacitors in your LCD TV or monitor and actually see if they are bad.
If they appear bulged on top, then they need to be replaced.
New capacitors will solve a host of problems in LCD monitors and TV's and will extend the life of your monitor or TV by several years.
Check the cables, connectors and connections.
Take it to a repair shop.

hi make sure the lamp door is securely fitted has there is a safety switch, thanks

shaun

If your LCD TV or monitor has stopped working, or is displaying one of the following symptoms, then it's a candidate for some new capacitors
- Flickering screen
- Screen image disappears after several seconds
- Dim screen
- Slow start
- Power LED on, but no picture
- Unusual colors and/or lines
The primary cause of LCD TV and monitor failure is caused by faulty capacitors. You can examine the capacitors in your LCD TV or monitor and actually see if they are bad.
If they appear bulged on top, then they need to be replaced.
New capacitors will solve a host of problems in LCD monitors and TV's and will extend the life of your monitor or TV by several years.
Check the cables, connectors and connections.
Take it to a repair shop.

The set may have shorted the horizontal out put transistor since it kept coming on sometimes. This could be cause by the driver transformer arcing causing a "spike" in voltage going to you horizoltal out put transistor. Stargazer

intermittent problems can usuall be liked to bad solder connections. And sony typically has some that will develop after a few years in the power supply. so check for bad sodler connections throught the main board & give a close look to the power supply & check you work after to make sure you have no shorted pins. good luck.