Laptop not starting and I can't see why

I have an Acer laptop and it's screen is broken, so I have a second monitor attached. The only problem is that the monitor stars when I am on lock screen, not when the computer starts. Yesterday, I decided to delete AVG because it was giving me trouble. I downloaded their removal tool and when it finished it required a reboot. When I rebooted, it didn't start normally. I tried rebooting again, plugging the laptop out and in the electricity, stopping my wi-fi router but no result. After a few times doing the things above, I saw something changing on my broken screen. I tried pressing different keys and found out that when I press Enter, or, for example, Down Arrow + Space, the laptop shuts down. I don't know what is happening because the monitor doesn't turn on (no, Fn + F# does not work). Any advice?