I think the "on case open" bypass was shown quite well in this video (the picture of the Surface device with a hole drilled in the back). Such measures should

I think the "on case open" bypass was shown quite well in this video (the picture of the Surface device with a hole drilled in the back). Such measures should protect against backdooring attempts (by the visible physical damage to the case) but they won't prevent an attacker from reading the secret key.