Rena pushed the gym's door, but the gym's door didn't open, the same thing which happens when you are in the under ghost or when you are being hunted down by the ghost.
The door doesn't open or then you faint, you get hurt all of a sudden out of nowhere, you start to see things like hallucination or illusion so that is what is going to happen now, not all but most of it.
"Pull it harder Rena! Or let me try please!" Liam passed through Rena's shoulders moving the door, he grabbed the other handle of the door.
He took a deep breath, with all of the power in his chest, Liam pulled off the door with all of his strength.
"Ppfft!" Rena giggled at Liam when the door didn't even move from its place.
"A- ah? Thre might be some type of jam in the door's mechanism, I think probably," Liam made an excuse for that but he was also sure that he was not going to get away with it.