Can you not get into the account? Or can you not sync it to your new computer?

Also, what OS are you using?

If you want to get rid of the problematic update, this could work. This method is if you are on the computer right NOW.

If you can use your taskbar to click on cortana (the search windows...

Shouldn't be a problem with an application. The steps in my post above will probably fix it. Did for me.

I figured out how to turn it off.
Settings -> Power and Sleep -> Additional Power Settings -> Change Plan Settings -> Change advanced power settings -> Display -> Enable Adaptive Brightness ->...

You can go into task manager, click on the tab that says startup, and it should show you what apps are impacting your startup. you can turn off stuff that you don't need or want.