So why didn't they replace just the CPU? And you should've had your computer with Surge protector to prevent this as well. Did they even give a good reason they couldn't just replace the CPU? What I can find on Bookmark transfer is the computer with the bookmark is where one does the transfer to move to new computer then finding it is next assuming these tips work.

"How to retrieve bookmarks from a dead computer." https://support.mozilla.org/en-US/questions/1003872

First, set Windows to show hidden files and folders:

https://support.microsoft.com/en-us/windows/view-hidden-files-and-folders-in-windows-97fbc472-c603-9d90-91d0-1166d1d9f4b5

Second, find the relevant profile folder on the old drive. For reference, I'll call it the "E" drive, but this would be whatever letter is assigned by Windows. Explore up

E:\Users\<username>\AppData\Roaming\Mozilla\Firefox\Profiles

That Profiles folder typically contains at least two subfolders whose names combine a random portion and a descriptive name like "default-release".

Within each individual profile folders double-click into the bookmarkbackups folder to see whether it has up-to-date backups. The file creation dates are embedded into the file names, for example:

bookmarks-2024-11-22_2498_gibberish=.jsonlz4

Third, copy/paste one or two recent bookmark backup files (these are compressed, so not directly readable) to your desktop for easy access. Then try the Restore feature described in the following article. You'll need to use "Choose file..." to point Firefox to the file you pasted on your desktop:

Restore bookmarks from backup or move them to another computer

Success?