I don’t think you will get any real answers on this board save everything is a fake.
Now the board is just a tool, like so many other tools, to contact other people in the spirit world. I would say your friend whose eyes had to be open was one of the controllers of the glass. This person would be a spiritual person with some experience with the spirit world. Let me know if I am wrong, just guessing.
I don’t use the board anymore, it is not necessary, but did use it a lot. I think what you experienced was very real. I used to get the same kind of results. The board is not a toy and will not work for everyone. But can be fun.
Don’t take to seriously the comments of skeptics who have never experienced or studied anything spiritual.
Love