Precision T5500 won't boot after Microsoft update - Windows 10

Windows 10 just did update, powered down to complete update process and now computer will not start.  Power light is solid amber, diagnostic lights 2, 3, 4 are flashing.  Can't get past this point....no display at all.   

Additional info....it will not power down, if you press power button and hold, it immediately powers back up and begins flashing the 2,3,4 lights.  I then pulled the plug, all of the lights went out, then as a last gasp...the 1&3 lights flashed along with an amber power light before it went dark.

What to do next??