AVAST UPDATE 7 FEB 2017 PC Boots to black screen

[REDACTED]

Updated Tuesday, 7 Feb 2017, when prompted by AVAST popup, my own defenses uncharacteristically down, but oh well.  Then woe is me!  PC only reboots to black screen, no cursor, and monitor power light blinking.  It’s my homebuilt machine running WIN 10 64bit.  Any help would be much appreciated.  Composing this in most undignified fashion on my wife’s Ipad, so my plight is real.
Thanks in advance, Paulus

[Eddy]

Boot in safe mode then try normal mode again.
If this fails
- roll back to a date prior to the latest avast update
- remove avast through control panel
- run avastclear
- install the latest avast version with the offline installer