Phone not displaying anything after viewing Snapchat.

Hey my phone screen went black while on Snapchat. Now this is the third time that this has happened. The first time this problem occurred my screen went extremely dim to the point where you could barley make out anything, but I was still able to interact with the phone. After noticing this I rest my phone using the slider and my phone was normal again. The second time the problem occurred I wasn’t able to see anything but I was still able to interact with the phone despite not being able to see. This time I hard reset my phone and the display popped back on. Now this third time the display is not coming back on at all even after hard resting it, and when I do hard reset it i’m not able to see the apple logo to know if I rest it right. The only way that I am able to tell if the phone hard rest is if the phone is unresponsive. Now this problem seems to only occurred when I was on Snapchat and resting seemed to always fix the problem, but now resting the phone isn’t working anymore. Also when I try to charge my phone now the extreme top left near the camera gets hot really fast. Any Idea’s on what happened and what I should do