Vizio m550nv amber light is on but tv will not power on

https://support.vizio.com/s/article/M550NV-Model-Information?language=en_US#

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.

Vizio 0500-0612-0030 Power Supply / LED Board for M550NV

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Vizio 55" M550NV 0500-0612-0030 LCD Power Supply Board Unit Motherboard. ... Any tears or bad connections between boards must be replaced FIRST. 2.

EASY HOW TO FIX LED Vizio TV- no power - YouTube

? 6:13
https://www.youtube.com/watch?v=9xZcTWr2yV0
Nov 5, 2013 - Uploaded by Tampatec
DiY How to Fix led / lcd Vizio TV service repair - no power service repair ... I can not get it to power on so I ...

If you can see the Logo; the back light is there. Contact any service technician; Sounds like main board fault. In most cases, a firmware update might help you. If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience. http://electronicshelponline.blogspot.com/

Try this thread : SOLVED VIZIO M550NV NO PICTURE NO SOUND It sounds like the same problem that you have.

Test the power supply voltages and see if some are missing or incorect, if they are replace the power board

Sounds like your using an old HDMI cable. You need to get on that can handle HDCP. Walmart has a few decent ones that cost around $14 for a 3' cable.

Hello
Just do this first and determine the fault. Connect your Vozio to an external antenna, to its antenna socket, and set it to autotune. You can refer to its user manual to how to do this. Let the TV tune all transmitting stations at that time, and memmorize it. After auto tuning is complete. select the channels one by one and check if they are perfect in every respec or not. Itf they are perfect, your cable TV operator is lying. As I know, Vizio is a perfect set. Do the above and determine. If the transmitting stations are also bad, surely your TVs tuner has damaged, and should be replaced with same type and number.
OK.

I had same problem. Unplug set for 10minutes then plug it in and let it go thru it's startup routine.