Same thing happened on my L435. I was able to install every build up to 10149. I got black screen sad smiley on that build and now I'm getting it on this build as well. Seems like Microsoft doesn't bother finding fixes for cheap phones.
Two things -
Soft reset (Volume Down + Power)
It'll just restart the phone.
Hard reset (restart the phone, and while it boots up, hold down the Volume Down key to get an exclamation point to show up. Once it does, press, in order, Volume Up, Volume Down, Power, Volume Down).
This will erase all personal data so you can set up your phone like it was new, just on the current build of Windows 10.