Display Won't turn on after unplugging power supply

A few weeks ago I tried unplugging my razer laptop from its power supply and my display automatically turned off. I thought this might be a battery issue but I have since replaced the battery and the issue still persists. I have it currently hooked up to an external monitor with only the external monitor showing. When I unplug the battery with just the external monitor showing, the computer still works. When I then unplug the HDMI, the laptop display never pops up, however the LED lights are still on. When I duplicate the display and unplug the battery, everything works. It's only when I unplug the HDMI does the display go blank again. I'm really confused because I'm pretty sure my laptop monitor is marked as my main display as well. Please help.