So, with my now upgraded Windows10 Surface3, I downloaded an app to change the login image (http://lifehacker.com/this-utility-can-change-your-windows-10-login-image-1721713560). Now, when I boot up, I get a series of flickering images--lavender screen, black screen, and lockscreen image. I frankly wouldn't even hard resetting the unit (I don't have any vital data stored there), but no idea how to do that. Trying not to panic...