HELP me with 9 level walkthrough

[SHPRD95]

here i'm recorded video
https://www.youtube.com/watch?v=96PujuwEJJ8
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help me, in room with three big statues and teleports ( III-II-I-III) i found key, but when i go back, big iron door not opened. Maybe i miss something ?
Sorry for my bad english

[Dr.Disaster]

When you're running around in the dark it's highly likely that you miss something. There is not even a puzzle involved but when you don't see it .. well .. you don't see it.

[SHPRD95]

When you're running around in the dark it's highly likely that you miss something. There is not even a puzzle involved but when you don't see it .. well .. you don't see it.

Thank for answer, but it's not a point of problem, because I'm turned off the light only in video. And if I restart from previous level, this happened again
one more video, but with light - https://www.youtube.com/watch?v=G2JWRJgY0q8