Players encountered a possible error when challenging the hard mode: after the red dead eye's health was reduced to zero, all enemies were cleared, but the expected exit door did not open. This problem occurs quite frequently in hard mode and is probably a bug.
1. In hard mode, after players successfully defeat the Red Dead Eye and clear out all enemies, they may encounter a situation where the exit door fails to open.
2. This door-opening problem often occurs in hard mode, and it is most likely a bug. Some players may try multiple times in a row but fail each time.
3. The current temporary solution is that players should contact customer service to report the problem and wait for a fix.
4. Before this bug is fixed, players can choose to play on normal difficulty, or try to restart the game to see if the problem will disappear on its own.