Holes were drilled in confidence that a different 12v thermostat would work.... and well it did not :(
I will chock that up to learning experience for the readers to benefit.
Although it is smaller so you may have one hole to fix. Or might be able to be positioned to cover both. Did not really verify.
To fix I used pressure to flatten the small ridge from drilling. Filled with silicone caulk. Then using a razor knife cut a small amount of wall paper material from an unseen area under the bedroom window. Cut it down to minimal size (2 or 3 mm) and is held in place with the silicone. Not perfect but you would not see it unless pointed out.