If you are getting this after a cold boot, then it can't be the driver, because it hasn't been loaded yet. I would check that the card is seated correctly by removing and re-inserting it.
You can force Windows 10 to fully shutdown (rather than hybernate which it what it does by default) by holding SHIFT whilst clicking on Start, then Power, then Shutdown.
Just an update.
I thought to uninstall the Graphics card driver (checking delete drivers) and restart.
This caused the GT635 to fall back on the default Microsoft Graphics driver, and the black screen flash on lock screen was gone (it fixed it).
Funnily enough after logging in, just like the boot screen everything was pixelated and weird, then after awhile Windows auto updated to a Geforce driver (an older version) everything snapped back to normal.
Now I think the pixelation is caused by the fact I am using 125% scaling in Display Settings (which the default Microsoft graphics driver struggles with).
Anyway pretty happy, so I open up Geforce Experience to update to the latest driver again for security reasons (latest driver was already downloaded and stored in temp).
And the black screen issue is now back. . .
Maybe it is a issue specific to the GT635 or similarly old cards, but the Geforce driver seems to be the culprit. . .