Power button led solid amber

Check this page-- Precision T3500/T5500/T7500 Workstations Diagnostic Lights and Beep Codes | Dell US

.You should post your exact model when asking a question.

Thanks for your link! I have contacted Dell support, and they couldn't find a problem with my system, thought it might be related to recent software installation. 

This computer is a 3240 Dell Precision workstation, small form factor. I5 with 16 ram, 254 SSD. For some reason it failed after having it working just fine for a week (before software installation). Then did not turn on with power button (no lights anywhere). Dell diagnosed motherboard needed replacement after multiple different testing including removing SSD and memory, etc. All to no avail. So a technician sent to my house and replaced mother board, seemed to work fine. Power LED light was white when it was on, and in middle of software installation done remotely, it turned amber. It does appear at times nearly white, then changes to light amber color. No blinking codes so far, and seems to boot up fine. BIOS and 2 other Dell updates were done (during BIOS updating, the LED light was white), but immediately after booting up turned amber again. 

DELL support said to talk to software installer, and then maybe consider reinstalling Windows Pro 10 (which is now has) and reinstalling software again. 

Looking for answers or ideas as to why the light is mostly amber, but occasionally nearly white--weird to me.

Thanks in advance for any help/ideas

Hello,

you said you reinstalled win10 . how was the power led after doing it and BEFORE adding back the software ?

Before software install the LED light was correctly white. Half way through installation, it turned amber and has stayed that way. Have not yet reinstalled Win 10 Pro, but did uninstall one of the software programs, Dragon speech recognition last night, and no change. The other program I cant find under "uninstall" setting, but found it under the "software" folder on the C drive. Both were installed through TeamViewer remotely for my work.

Noticed that when I start computer in BIOS, using F2 button, it stays white, but when going from that to regular startup the LED light is still white for maybe 3-5sec, and then slowly becomes amber.

Understood.

well, I would avoid reinstalling the os, for now. A simple quick and painless test would be to download any linux live distro , make an usb boot thumbdrive with it, and boot from it using F12 at power on.

This way you can evaluate the led while another os is running, not so different vs reinstalling but less messy and more painless for this scope.

I finally downloaded from Dell the OS repair on USB device. Used it with F12 key on starting computer, and did a new install of OS with it. Took several hours overall, and after that LED still is the same. Starts out white and then changes to light amber, called Dell again, and was told after doing a few more checks the behavior was probably ok. So we'll see going forward. Meanwhile, the possibly offending software installation is blown away and will have to be reinstalled again!

Lots of time spent. Asked about if the PS could be borderline on CPU load, and was told it should be okay as there are no blinking lights on LED or other unusual behavior.

Might need to power down and clear cmos.

Solid amber power button indicates a problem.

Still unresolved problem. Computer still working fine after recent remote software installation. Dell has escalated problem to hopefully someone who may know the answer for the yellow LED light.

The 3240 is around 5 years old.  Try replacing the size 2032 CMOS battery.  They're good for around 5 years and cause problems when they go bad.

https://www.amazon.com/s?k=duracell+2032+battery&ref=nb_sb_noss