I Fix Air-Conditioner

The hearse with the weird odor slowed to a stop before the entrance. The sound of pebbles could be heard bouncing on the ceiling. There were footsteps coming from the corridor, and there seemed to be someone sawing next door. The door knob to the room rattled slightly, and the faucet in the bathroom kept dripping even though it had been screwed shut. There was a rubber ball that rolled on its own underneath the bed. Wet footsteps started to surface one after another on the floor. 
At 3 am, Chen Ge held a cleaver in his hand as he hid beside the room heater. The call he was trying to make was finally answered. "Landlord, is this what you meant by 'the house can be a little crowded at night'‽"

Millman97

My House of Horrors

Lonelytree

Daoist6fubtiW

Wang Haiming was possessed by something inside the mental hospital, and the thing followed him out when he exited the hospital. Both parties were constantly fighting over the control of his body. Wang Haiming decided to die rather than compromise.

The man's weird death and the actions that happened at midnight supported Chen Ge's speculation.

After Wang Haiming's death, the thing he carried out with him from the mental hospital probably stayed back in this room. When his body was carried away, there were plenty of police and spectators, so the monster definitely did not show itself. When night came, Room 303 was sealed, and the monster had no chance to go look for a new target.

Sleepwalking?