Help needed with: This does not appear to be a sketchup model

Hi,
Recently my iMac crashed, while my external ssd drive with my sketchup folder as one of the several folders on that ssd was connected to the iMac. I had to do a complete reinstall of the mac operating system and reconnected the external ssd again. since then, the folder called sketchup, containing SKP, PDF and DOCX files, show all the files I require, with content showing in “info” as expected. However once I open any of these files, non wants to open and the message I get with SKP files reads “This does not appear to be a sketchup model”. Other folders on that drive work perfectly, such as Videos,Pdf and Docx files,
I have attached two SKP files with that problem:

Luff.Desk.Exist.FLP&Elev.skp (383.6 KB)

Luff.kit.ELEV.A.skp (964.7 KB)

Unfortunately, both files contain only zeros. They cannot be recovered. :frowning: