Dell XPS 9550 solid white light and no boot

I'm assuming windows 10 is on the system....

Solid white mean AC adapter is connected and the battery is charging. Solid amber means Battery charge is low or critical. Please run Dell Off Line diagnostic to check status of the battery health by following steps below.

1. Power off system

2. Power on system, quickly start tapping F12 key continuously until you see Preparing One Time Boot Menu in top right corner of screen. In Dell Preboot menu, select Diagnostic. After quick tests, select Primary Battery and then Thorough Test Mode. Report back any error code.

How to Check Battery Health Status on Dell Laptops

https://www.dell.com/support/article/en-us/sln143156/how-to-check-battery-health-status-on-dell-laptops?lang=en

If there isn't any error code on the battery:

1. Power off system

2. Power on system, quickly start tapping F2 key continuously until you see BIOS setup.

Check the status of the AC adapter in the BIOS menu.The adapter should say it's type. If adapter says Unknown or None then it's an issue with either the adapter, DC Jack or mainboard. Please note the AC adapter will continue to power the computer but will not charge the battery.

XPS 15 9550 Specifications

https://www.dell.com/support/home/us/en/04/product-support/product/xps-15-9550-laptop/docs

Thank you but the light is coming from the power button not the light near the trackpad which is off. I have tried all these commands yet the computer seems to be dead other than the one light.

 " It turns off when I unplug it making me think it is a battery issue "

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I went back and read your first post again. Does the computer boot into windows when AC adapter is plugged into the computer? If yes, please disregard reseating memory and the other components. Just reseat bay battery to see if it will get the computer to start on battery power. If computer doesn't start then most likely, battery is faulty and needs a new Dell battery.  

How to Troubleshoot Dell Laptop Battery Issues | Dell US

https://www.dell.com/support/article/en-us/sln292953/how-to-troubleshoot-dell-laptop-battery-issues

And check out the video below.....

Dell XPS 15-9550 Battery How-To Video Tutorial

https://youtu.be/ujYLT45FiYU

If you're comfortable removing base cover of the computer, I'd suggest reseating one component at a time such as bay battery, memory(RAM), graphic card if any, coin cell battery to see if any of them will make a difference.

Note: Please read service manual thoroughly before opening the base cover of the computer

XPS 15 9550 Service Manual

https://www.dell.com/support/manuals/us/en/04/xps-15-9550-laptop/xps-15-9550-service_manual/procedure?guid=guid-43536922-33c8-4e6f-aa8a-6da9fa993555&lang=en-us

First, reseat bay battery. This step usually will fix this no boot problem.

1. Power off system. Remove AC adapter, all peripherals such a printer, external hard drive, flash drive, speakers, and then base cover. 

2. Remove battery. Press the 'Power On' button for about 15 seconds to drain the residual power

3. Replace battery, base cover, power on computer. Hopefully computer start normally. 

If you aren't comfortable opening the base cover and reseating components inside the computer then I suggest you contact Dell Out Of Warranty in link below and request a quote on repairs.

Fix Your PC or Tablet | Dell USA

https://www.dell.com/en-us/shop/fix-your-pc-or-tablet/ab/fix-your-pc-or-tablet

It does not boot at ALL  

@LSUFAN51 

MoolaLove747EC

Does computer boot into a black or blue screen with AC adapter connected to it and  wall outlet? You're hearing any beeps? You reseated the battery ? 

Dell PC does not turn on or boot into Windows | Dell US