What should i look for or do for this tv?

Several possibilities but most common seems to be power supply defect or poor connection. Check these resources. Note that other Youtubes that may address the problem are also accessible from the youtube link.
LG Smart TV Keeps Turning Off then On Again
Lg Du 42px12x shuts down fix
42 in LG LCD TV turns off by itself

I’m happy to help further over the phone at https://www.6ya.com/expert/donald_f2ed37026a3ac881

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. Surf the site with patience. Pull up older posts.
http://electro-medical.blogspot.com/
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.

No doubt. Fault to the main power supply regulator section. Either it will be a separate board, or the part of main board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts.
http://electronicshelponline.blogspot.com/
It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.

Did it work with the Y-sustain board replaced? Likely if it did not work then there is an issue with the capacitors on the Y-sustain board and the power board. Check these caps for failure and replace them with the exact type. Likely the caps are blown and cause voltage loss in one or both boards.

On your Samsung remote. Press the MENU button. At the botttom of your screen you have the setup selections. Scroll over to the SOUND option and select that, A menu should appear and toward the bottom of the menu you should see MELODY. Scroll down to that and select ON or OFF...

Firstly you should not unplug your computer for long times. Inside is a battery to keep the BIOS alive. When you unplug it, it flattens the battery and if left unplugged for a long time, it kills it. This means that the BIOS now starts in default mode, which can lead to many problems because all the custom BIOS settings are now lost forever or until you or someone else change them.
Change the battery on the motherboard and try again.
The reason why the LED was flashing then stops, is that the battery has a small charge enough to be stable. Now that your BIOS battery is dead, you will never be able to charge that battery again, so replace it.

sounds like it's toast http://community.sony.com/t5/Television-Picture-Sound/Vertical-Lines-of-death-KDL-52W4100/td-p/29582

I have the same issue. I read and watched online tutorials about the compositors but after opening the set up I was unable to find any that had gone bad. I was able to upgrade the software by using a USB thumb drive but the issues are still there. I'm thinking of swapping out the motherboard and/or the power board next to see what the fix is.