I have two identical Dell Latitude E7470 laptops. On each of them, when I got them I booted a Fedora Live USB stick, installed gparted, and used it to shrink down the Windows 10 partition to make room for Fedora. I have done this process on a lot of laptops going back a lot of years, and this is the first time I have seen this problem.

On one of the laptops, as soon as I boot into Windows 10, I can no longer boot Linux. GRUB is somehow trashed and the only way to boot the system is to select "Windows Boot Manager" in the BIOS, which successfully boots Windows 10. The other laptop does not have this problem; I can boot Windows, then get the usual GRUB menu at the next boot and select either Windows or Fedora, and all is good.

Has anyone ever seen this kind of problem before? Is there a way to recover GRUB? Last time this happened, I ended up having to completely reinstall Fedora to get the system back to dual boot. It has now happened again and I would like to avoid having to reinstall to recover. I would, of course, also like to prevent this from happening in the first place.

The systems are both using EFI boot, without secureboot.

Thanks for any insights,
--Greg