I was extremely frustrated, but not at the product. It was clearly user error.
Watch the video several times. If you follow the instructions, which I am usually good at, it should not be a problem. Make sure your working on a level surface, found that the desk I was working on was not completely level, which caused the glue to move to one side. Make sure you pull the pin at the correct time or too much glue will go to the bottom. Make sure you wait 100 seconds without touching anything to make sure the glue fully disperses.
I did not ruin the glass protectors because I never tried to cure the glue. Once I realized the glue did not have complete coverage under the glass, I stopped. I just cleaned the glue off the glass protectors with soap and water.