Phone on, No Display So my aunt told me to fix her android phone and here's the problem. After the android logo and text splash screen during the boot up, the screen is all black but I can still open applications ( just by randomly tapping the screen ) and I know they work. 

Is it a hardware related problem?
I think you need to flash stock rom in your device , the working of applications ensures that your device is not bricked.You might not be able to boot your phone in recovery mode which will not allow you to Factory Reset(you woun't see any content displayed due to splash screen) so you need to flash stock rom by third party applications from PC such as SP Flashtools,Odin,etc according to your device.