To my knowledge, no citizen has ever been prevented from reentry due to a blank or absent device. In fact they cannot block a citizen’s legal reentry for any reason, they can only detain you while they investigate.

Beyond this, “I dropped my phone in the ocean” is always a perfectly valid reason.

If you’re a foreigner and they already suspect you of something, they can deny you entry for any reason. It may be better to be denied than arrested!