I has same thing happen to me yesterday. Banged my head against a wall multiple times until I turned my TV on ( 2nd monitor). Seems like Windows 10 doesn't like 2nd monitor at all so I had to physically pull the plug on my TV monitor ( disconnect a cable). I also to set my main monitor as primary to my desktop too. If you have only 1 monitor, boot to installation disk > (F8), go to safe mode with networking and see if it works. Try to update video drivers while there. Also in safe mode go to Power Options > Choose what power button do > Change setting that currently unavailable, and uncheck Turn On Fast Startup.
No you don't have to sign in to Microsoft account. I never did and everything worked for me just fine. It did took a while for activation to kicked in ( 2 hours) but it worked. If you see activation error messages, wait a little while.