Macbook Pro Retina 2015 display issue on startup I'm having some trouble with my MacBook Pro Retina display.

When it  starts up, the display momentarily shows strange colours in 'blotches' on the screen (see image). This just lasts for a couple of seconds before the regular login screen shows up.

Is this likely to be a hardware or software issue? I had a warranty repair on it about 18 months ago and since then the screws on the bottom keep loosening, so I'm not sure if this is connected.
This is most likely a hardware issue since the weird colours appear before the login screen loads.