I would contact the seller first, they should send you a replacement. If not you will have to remove the overlay from the screen.
I have removed glass touch overlays before. Either put the monitor in a car sitting in the hot sun for a few hours or in the oven set at 125 for an hour or so. This will help release the double sided tape from the two pieces. Now comes the tricky part. You will have to acquire some 3M VHB tape. You can order it online, just do a search. Apply the tape and make sure that all 4 pieces are perfectly butted up against each other to prevent dust from getting under the overlay. You will need some isopropyl alcohol and dust free wipes to clean the the surfaces making sure to remove all of the dust on the screen and both sides of the overlay. The companies that attach these overlays do it in a clean room, free of dust, so you will need to work fast after cleaning the surfaces to minimize dust entering the cavity. From here, you can just eyeball the placement of the overlay on the screen. be certain to identify where the functional part of the overlay is, I believe it it offset a little. Center it over the screen. Any misalignment, within reason, can be overcome when you align it via the ELO software. Apply firm pressure to the overlay making sure that the tape is attached to both surfaces.
Good luck!