What you may try, is to boot the host from an ESXi 6.5 installation media, without actually installing ESXi to find out whether the VMs are still accessible.
To do this boot from the media. At the ESXi 5 seconds count down press Shift-O, delete runweasel from the boot options, and press Enter. Once ESXi is up, you can login using root with a blank (no) password.
Caution: The above may modify data. If you plan/need to have important data restored by e.g. a data recovery company, do not try anything that could make things even worse.
André