Cannot log in after update to 10.12.3

Hi, after yesterday's update (macOS 10.12.3) I cannot longer log in into my mac.

First of all, everything was running smooth on my Mac. Last time it was restarted was around 40 days ago, I went out on a quick vacation so it entered sleep mode for around a week. Other than that, normal use, no issues.

Yesterday I went to the App Store to install the OS latest version, after that it restarted as normal but stayed on a black screen and from time to time this image would appear and lasted only for a second or 2, so most of the time the screen is completely dark with no cursor or anything else.

After some 20 minutes I understood that something happened and restarted the Mac. Everything went on as normal, booted up, arrived to the login screen (I only have one admin user with filevault on) and entered my password. Pressed enter and then the same symptoms: A black screen with nothing else and from time to time I see that wheel in the image above but only for a second or 2.

I decided to try to boot on verbose mode (read that on the internet). Reached the login screen, entered my password and the last message I got was: "HID: Legacy shim 2".

Any idea?

Thanks, I'm going crazy, this is the first time I have such a big problem with my Mac and no idea on how to fix it.

Message was edited by: t4ggs