is it illegal

Solution
Don't know if it's illegal, it may be if you set a password on the thing and they try to bypass it. Handing them a phone with your files on it, don't see how it can be illegal to look at what is on the device. If they copied the files and posted them or used them for something themselves, that may be illegal. Say if they found pictures of you and then used them in an ad or copied a file you saved your passwords on and then used them to steal money from you or send you spam email. Just going through files on an unlocked phone that was handed over may be immoral but I doubt it's illegal. If you are worried about things, just lock the device with a password unless whatever work they are doing needs it unlocked. Changing a screen...
Don't know if it's illegal, it may be if you set a password on the thing and they try to bypass it. Handing them a phone with your files on it, don't see how it can be illegal to look at what is on the device. If they copied the files and posted them or used them for something themselves, that may be illegal. Say if they found pictures of you and then used them in an ad or copied a file you saved your passwords on and then used them to steal money from you or send you spam email. Just going through files on an unlocked phone that was handed over may be immoral but I doubt it's illegal. If you are worried about things, just lock the device with a password unless whatever work they are doing needs it unlocked. Changing a screen should not need any access to the device past testing touch which you can do with the lock code screen.

You'd want to make a backup of your device also before handing it over just in case something happens.
 
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