Didn't dropped it prior to this incident. No cracks in the display too. It flashes a few green, yellow and white vertical lines every now and then too, whenever it should display something (like the Samsung logo or whenever I tap the screen that should display the lock screen).
I know that the phone is still working because it sounds upon start-up and whenever I plugged it in the charger. The display is also responsive because I hear the number keypad sounds (I assumed I tapped the "emergency call button" in the password prompt in the lock screen). The Samsung find my mobile also shows our wifi and the battery level, other remote features won't work since I haven't turned them on before. I would like to open it thru windows your phone app or dex but I can't until I can successfully enter my password in the lock screen.
Booked an appointment already in the service center but I hope I can exhaust all the ways to check the problem and to also back up my data..
Update: I charged it for a while and the whole screen lit up with color white for a while and then proceed to a green/black flickering display then went back to black screen. All the pixels seemed working. This is so weird. https://youtu.be/3mBD1QyG-Iw