@secondlife great description. You got a lot going on here. This “If I remove the bottom case, the problem completely disappears “ sounds right about your aluminum shielding causing it to somewhere shortening out when flexed. Try to line the shielding with something non-conducting and see if that resolve the issue. If so, I’d remove most of the shielding from the back of the case and double check it after that. I do not think that we can manage to totally pinpoint where the point of contact would be