(10 hours ago)Petey Wrote: Any chance to compare the current boot config with an OS backup I created after installing Hasleo and check for differences?
You could take another backup of the current boot partition and then mount both partitions (the old one that didn't work and the one from the current backup) with HBS.
Then there's WizTree, a tool that is normally used to find big files on a partition. That tool offers to export a CSV file ("Export to .CSV") with all the files and their sizes and change dates.
With those 2 CSV files on hand, you can then compare those with a tool like WinMerge to find differences in the file structure.
It's maybe not the easiest way to find diffferences between 2 partitions, but I do this very often and it works for me.
Keep in mind though, that this will only compare the file structure of the partitions. The differences could also be somewhere else like in the boot entry itself or corrupt boot sectors etc.