Corrupted HDD. Restored it with TestDisk. Cant open restored keys in GUI?

Question

Last week my HDD corrupted. I was able to restore it and save most files with TestDisk. However all files are named such as "F26689223" instead of their original file-names. With a keyword-searcher, I was able to find most of what I was looking for, except for my seed-phrase. I have around 45,000 txt-documents that are 1 kb, so it is like looking for a needle in a haystack. However, I recovered around 18 .key files. These I cannot open in the XMR GUI, I'm not sure why.

When I open them in notepad they start with either:

-----BEGIN RSA PRIVATE KEY----- 

Or this one:

-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: (Numbers)

Answer 1

These I cannot open in the XMR GUI, I'm not sure why.

That's because those are not a wallet .keys file. The wallet .keys file is a binary file, not a PEM encoded RSA private key.

Good luck with your hunt.