> They will bill/sue/evict you for tampering with the entry locks, for sure.
I'd have a hard time believing anything comes of it if they try.
Let's say:
* You contacted the landlord and let them know the lock was not functional and you'd been unable to access your unit on several occasions. You'd had to sleep at friends' houses several times due to being unable to access your unit. You give them a reasonable timeframe within which to respond appropriately given the severity of the situation (i.e., replace the lock the next day not just send you the phone number for Latch tech support).
* The landlord did not appropriately resolve the situation.
* You replaced the lock with a simple keyed lock without damaging the old lock. You then immediately notified the landlord and provided them a copy of the key. (They also have a legal right to access the unit.)
Where I am, you have committed an act that is explicitly contrary to statutes governing residential tenancies. However, you did so in response to what was effectively an illegal lockout. (It doesn't matter if their intent was to improve the unit--they effectively restricted you from accessing it when you have a legal right to do so.)
They can:
1. Bill you: They can send you some paper. The question is how they enforce collecting the money. It's possible, though unlikely, they _may_ be able to obtain an order for "damages". In this case that would amount to about 15 minutes of a their maintenance staff's time to put the lock back. Using the typical rates I've seen the boards here use for that kind of unspecialized work, you'd be out about $5-8.
2. Sue you: For what? What outcome are they trying to have the court enforce? The court isn't going to order the lock put back and effectively enforce an illegal lockout.
3. Evict you: They already tried to do that via an illegal lockout. I cannot see any board here ordering an eviction in response to changing locks in a way that the landlord's access was never restricted--it's completely disproportionate. They're also generally not going to order an eviction over something that could be easily rectified without an eviction (put the old lock back on, matter's settled, everyone go home).
The "courts" are people, not computers blindly applying a set of instructions. If their options here are (1) to enforce putting the lock back and lock you out of your unit; (2) to evict you because your smartphone isn't compatible with the lock the landlord wants to use; or (3) tell the landlord to kick rocks and fix their damn locks, I'd put my money on #3.
(I'm an involuntary landlord in Canada. I've had to argue in front of a tenancy board--the "court" with original jurisdiction over disputes under the tenancy act--a time or two or thirty. In preparation for that, I've probably read more previous decisions than some of the people _making_ those decisions. IANAL YMMV offer not valid in conjunction with any other offers or promotions HTH HAND.)