foreach my $listDevices ($device_list->result()) {
    ...
        open OVERWRITE, ">overwrite.txt" or die $!            
    ...
        close OVERWRITE;
    ...
}
[download]

Do you see what is happening?

You have even called the filehandle "OVERWRITE".

The file gets overwritten every time the loop and if directive come by the call to open

Solution: place both the open and close outside of the foreach loop.

open goes first, then the loop, and when that's done, close the filehandle.

Cheers, Sören