Lg3730 standby light blinks but never turns on

How many times this standby/power light blinks at one time switch ON? Count it carefully. These blinks are fault indication, and known as blinking codes. From the number of blinks occur at one time switch ON; you can get an idea about the faulty circuit stage inside the TV. This will make repair easy. For more information, check the link http://electronicshelponline.blogspot.com/. If the blinks continues, and non-stop, the fault should be with its main system control IC, and with the memory IC.

Blinking of standby light to Sony TVs are fault indications. How many times this standby light blinks at a time.

On Sony the standby or red is for shutdown---

If you unplug the set and plug it back and turn it on and it repeats this look to see if the light is either constantly blinking or blinking a specific number of blinks---specific number would be an error code.

In standby mode (red led on/after the led stops from blinking), press "Display", "5", Volume (-)", "Power on" on the remote control in sequence, self diagnostic screen will be display, let me know the what is on the screen to diagnose where the fault came from.

Count the number of blinks of the standby light. It will bink a count, pause and do it again (Common counts are 2 -9) Give this count to a Sony service center and they can help you know what the issue is. (Probably the lamp)

Please check batteries in remote that seems not working. Sony TV would either turns On or standby light will blinks if TV gets any internal problem.
You question shows standby light stays On that means TV does not receive power on command from remote.
If standby light is blinking in sequence, let me know how many times it is blinking and also intimate exact model number of TV to find out possible solution.
Thanks.

Those blinks [flashes] are fault indication (Error Codes). From the number of blinks occur at one time switch ON, you can get an idea about the faulty circuit section inside it. This will make repair easy. These are called blinking codes. Make sure about the exact number of blinking of the standby/power LED, by switching On & OFF the set, for at least two times. Count it carefully. If you wish to get some details, check the site linked here. It has details about blinking codes, and fault locating procedure, to many popular brand TVs and other devices.
http://electro-medical.blogspot.com/
http://homenol.blogspot.com/
http://electronicshelponline.blogspot.com/
If blinks continue without any pause, the main board is faulty.
Search the site by type in the "brand name" to your device, in the "Search box at the top right of the display window of the Homepage" to get gathered related posts.

When attempting to turn on the set, the standby light should blink for a a while then stop once the picture comes on. If a problem is detected internally, the standby light should blink in a repeated pattern. Please count the number of blinks that are repeating and we should be able to help.

Thanks,
Dan

The key here is the number of blinks of the standby light. This is an internal diagnostic code. Please provvide that count and I should be able to suggest possible fixes.

Thanks,
Dan

That means current overload transistor Q5001 or Q5201 is shorted on the D board and must be changed