I found a hack for pulling the lock screen down, in case you have installed Android AOSP 7.1 (Nougat) on a non-phone or non-tablet device like me, which does not have touch screen, and therefore cannot physically swipe your screen up as told before login. You connect two mice to the USB-ports. One of them is used to pull down the invisible settings panel with click and drag. While holding down the left mouse-button in the drag operation, you take the other mouse and move the cursor to click on for instance the settings wheel. After this the password dialog will show up, and you can type your password with your keyboard. I hope that this tip helps someone to NOT re-format their installation device to clear yourself of the lock screen, losing all of your settings at the same time. (Also make sure you install a shutdown application since you don't have a button to trigger the menu. It can corrupt data to just pull the plug on the power adapter.)
