Laptop screen black, lit, external display via hdmi works

It was working completely fine today, until I woke it up from 20 minute long sleep mode . The screen lit up, but didnt display anything. I was worried that either the hard drice got disconnected or the battery broke, but when I plugged it into a tv via hdmi everything worked fine. 
Any ideas? 

 

 

 

1.Unplug the AC adapter and other cables from your notebook.

2.Turn the notebook and look for battery reset pin hole.

3.insert the paper clip and hold it for 30 - 40 seconds.

4.Turn over the notebook one last time and plug in your AC adapter.

5.Turn on your notebook.

Or should I have disconnected the battery too? 

 

Also, when booting from another drive the same problemoccurs- does that mean it has to be a hardware issue?