Iphone x screen very Dim

Hi I recently got an iPhone X from my friend which has an issue. If the phone is off the charger it is extremely dim and one can barely read anything on the screen. When connected to a charger it brightens up slightly but still very dim. The screen also flickers especially when an app is in use.

I have updated the phone to the latest iOS version, and both a soft reset and a hard reset have been performed on the phone.

Please advise what could possibly be wrong, is this a screen issue, battery issue or possibly a problem with a connection inside the phone?