iPhone X black screen - force restart not working
I sent my iPhone X in for a small repair and just got it back today. I was able to use it just fine for maybe an hour or two before the screen completely blacked out while I was using snapchat. I could still feel the buzzing of the phone but the screen is completely black. I tried the force reset (volume up, then down, then hold the power button) many many times as well as plugging it in to iTunes but nothing is working. The computer doesn't even recognize that the phone is plugged it, but it does vibrate upon being plugged in. I'm feeling frustrated since this phone has been in repairs for more time than it has worked. Any help is appreciated.
iPhone X