If you demonstrate that government employees changed files all over your hard drive during a "search" then I wonder if recourse or compensation or legal action is possible.

I understand the law permits CBSA agents to perform warrantless searches. e.g. reading the contents of your hard drive. This is, rightly, controversial. But then does the law also permit them to modify the contents of your hard drive?

The act of logging in and browsing your computer will make many changes to system log files, to metadata of documents (e.g. last accessed date), etc. (Just thinking out loud about technicalities and other angles on this.)