PC won't boot, just black screen, flashing cursor

[Lysrin]

Sounds like you may have been hit by KB3140743 'bug' that is biting a lot of peeps in the ass.

How to Fix Issues Caused by Windows 10 Cumulative Update KB3140743
https://nh.reddit.com/r/Windows10/comments/48qs4y/fix_update_kb3139907_and_cumulative_update/

Very interesting indeed! This is not the first Windows update to cause issues for some, iirc, although in the past I have dodged the bullet.

 

[smith_more]

Restart your computer in Safe Mode then go to Device manager. Click on Display adapters category and disable it. Now, you will have to restart the computer again and it should work fine. If not then time to call technician.

 

[smith_more]

Seems like the new patch unstable the OS. Its time to format the PC

 

[clshades]

I had a similar problem with a client computer. Windows update installed an update for the hard drive and between the random black screen boot ups and not being able to install update error I finally figured out that windows installed a bad driver for the hdd.

Took me a lot of googling to figure it out.