First of all it's Level 2! Sorry for that.

Well i found one key for the door with the two locks, after pushing some rocks in and now I cant find the other one. The door, which is next to the double-lock-door, is open, but has a teleporter which just teleports me right in front of it again. Please help me.

If I recall that part correctly, turn your back to the teleporter, and in front of you should be a button. Throw something at it, then backpedal over the teleporter. It does require you to be fast, not sure how (or if) low framerate will prevent you from completing it.

What I do is press the wall button, then hold down (not repeatedly tap) S to walk backwards. Seems to clear it every time.

Thanks for the help. Worked perfectly! :)