I guess the description comes from a different smartphone and has been adapted incomplete!
1. Why remove the keys from the frame if you have already removed the frame from the mobile phone?
2. The suction cup unusable since the rubber is too soft and the liability is insufficient to the glass even one micro millimeter raise and normally the glass is indeed repeatedly torn so that you always have a plan under the suction cup so the already low Liability is who comes through the crack in the air sucker even lower.
Fortunately, however, we must on the glass, too often not paying attention when you remove, you get namely really only with the 2 plastic levers and 2 plastic discs on.
However, in this case but also take care that you pry the plastic rim around the display when not crushed !!!
3. The order of installation should you prefer not to comply or it could be that you tear off the top Flexband on glass when only the Flex Band performs the opening and only then secured the Klebebend!
4. The statement that is required it selectively and slightly wrong!
If one bears in mind, the glass at the slightest twist (what can happen in your pocket quite times) pops out and then breaks in your pocket!
So better only cut the tape into strips and like the original (which is, incidentally, also glued full-surface) mount possible over the entire surface in the housing.
Then clean the display case very closely on hair or other dust eighth when the glass is even there and you but some dust or similar has under the glass, it is bad if you still need to get the glass again!
Now pull off the back sheet of glass, lead the flex string through the hole and carefully fitted into the machine, then you can fasten carefully the Flex bands again.
The adhesive tape, unfortunately, only normal double-sided foils tape and not a not like the original, a thin double-sided foam tape should heat the glass with the hair dryer and press lightly on the edge to allow the adhesive sticks better. But not too much press so that the glass does not break again !!
Then you can screw it all again, assemble and remove the front sheet.
And if you did everything right you have now again a glass without crack in the mobile ...
I Wish You Success!