[webdoodle]

Software buttons can't be trusted. Smartphone manufacturers need to put hard switches on the power, cellphone transceiver, wifi, bluetooth, camera, mic and speaker. Also, all the major components should be replaceable, especially batteries.

[roynasser]

The architectures currently seen on cellphones and most (if not all) modern electronic devices make it so hardware buttons are just as vulnerable as software "buttons"... (the hardware buttons actually trigger software which maps it to functions, so if the software is attacked the hardware button could be vulnerable - just as a software button...)

The case for replaceable batteries can be made from a convenience/durability/sustainability point of view, sure, but how do replaceable batteries improve trust?

[vetrom]

If nothing else, technician-free battery replacement simplifies maintaining a personal chain of custody, and thus, longevity of the trustable life of a product.

Not a directly trust related issue, but an often conflated factor. (assuming you dont do something exceptionally silly like make the batteries have a serial interface and protocol that can be its own attack vector. Wait a sec...)