Black and white are displaying just fine but other colours seem out of whack, like as if its been inverted but it hasn't tried adjusting brightness etc but still very dark as if a backlight or a colour hue isn't working, suggestions please? Was purchased second hand as was 'dead' in actual fact the battery had had it and needed a new one, new battery = phone loading no problem! But this with the screen has me puzzled, motherboard issue or a new screen? HELP!
First, do a hard reset, and see if that corrects the issue, failing that:
You might try to do a wipe and reload of the OS. Back anything you placed on it (music/vids/docs/images) etc. and do a wipe and reload of an official OS release, not a leak (you may experience anomolies with a leak) and see what happens