Messed up migration from High Sierra to M1 Big Sur, please help

[WilliamTyl]

Hello, please can you suggest me what is the best way I can fix a huge mess that happened when a very incompetent shop migrated the data from the hard drive of the old broken laptop to the new M1? (macbookair 8GB Ram, 512GB)
What happened: old laptop was already messed up by someone who reinstalled my HD twice one inside the other and then tried to fix it by removing stuff randomly, so it took a lot of storage and was an unsearchable mess.
From that I only needed to salvage Mail (many files not in the folder), keychain access with all the internet passwords for blogs etc, books music and photos would have been nice, nothing more.
What the shop did: one guy didn t know how to migrate from an older back up, so he just copied the files on let s call it User 1. Then they tried to recover the fried hard drive, installing it in another laptop to migrate, that failed. Then they successfully migrated the old backup, in let s call it User 2, so in User 2 I have the 2 HDs one inside the other, but working emails and the other data. (And I think something else, it takes 180GB of storage). InUser 1 it s still relatively organized but there is a folder with again the HD, but this from the newer backup, with some working files I missed, plus another folder with the older balck up but not installed . NOW: is there a way I can bring the emails and passwords from User 2 to User 1 manually? So I can just delete User 2 and the HD sandwich it contains? And how do I delete all the unused stuff? O r can you suggest the best way to do this? After all this nice work I have 80GB free on a 512 mac book air I never used. Thanks

 

[Apple_Robert]

If I were in your tech shoes, I would transfer any important files you want to keep to an external drive for the time being and then do a clean instal of Big Sur on your M1. After the clean install of the OS and apps, I would manually move over files you want to keep on the M1 and leave the rest on the external.

Erase and reinstall macOS

Erase your Mac, then use macOS Recovery to reinstall macOS.

support.apple.com

 

[WilliamTyl]

After the clean install of the OS and apps, I would manually move over files you want to keep on the M1 and leave the rest on the external.

Please how do I move the emails from the old Mail to the new Mail? They were only stored locally, I had years of work contracts and such, that was the main reason to do all this

 

[Fishrrman]

OP:

It's time for you to STOP relying on incompetent "techs" to do your work for you, and to learn to do things for yourself.

The macbook air you speak of (that wasn't working)...
Do you still have it?

What Mac do you have now?

Do you have any other drives with data on them?

Your statement "2 HDs one inside the other" makes no sense at all.
We need a better understanding of what you're trying to say.

What kind of backups do you have?
On one drive, two drives?
What kind of backup app was used to create them?

Answer these questions, and perhaps we can get somewhere.