USB would add to the BoM. Much easier (methinks) to have the lock revert to the last known good configuration if you operate an I/O on the inside in an unusual way - say, turning the lock thingamajig towards the 'open' direction for >20s or so.

Also, no update should be carried out unless the user initiated it - for instance, a flashing led or an app notification tells the user an update is available - and it needs to be initiated by using the same controls as would be used for a roll-back, ensuring you do not end up locked out after updating.

That being said, the idea of a lock being online scares the bejeezus out of me. Call me a luddite, but as a minimum I want my burglars or vandals to show up, rather than nessing with me from wherever.