Latitude E7440 won't power, shows undocumented LED error code

I have a Latitude E7440 that will not power on, and shows two LED lights on the lid:  Solid white power light, and solid amber battery light (see attached image).  These lights show constantly when AC adapter is applied or when laptop is docked.  On battery, they show for around 15 seconds after the power button is pressed and then turn off.  No other lights come on, only the external LEDs mentioned.  I have tried removing the battery, using AC adapter only, re-seating internal components (RAM, HDD), etc. with no change in behavior.

This problem began when the laptop was turned on, lid closed, and placed on a new ePort docking station.  At that point something happened to cause the laptop to lose power, and ever since it will only display the two LEDs.  I do not see any listing of what problem this combination of LEDs might mean, has anyone seen this before?  Thank you for any insight!

Tim