The hardware is yours. If you want to blow away the firmware and write your own, no one can (legally) stop you on copyright grounds, though it might lose its street-legal status in the interest of the people you might manslaughter by writing buggy code.
It's where you want to modify the software and post a derivative work online that copyright law kicks in. You may as well say that you do not "own" a book, because you don't have the right to share an edited version of it. Sort of true, but not very interesting.
It's where you want to modify the software and post a derivative work online that copyright law kicks in. You may as well say that you do not "own" a book, because you don't have the right to share an edited version of it. Sort of true, but not very interesting.