Another "know-it-all" who assumes everything.
You can manually unlock by turn a knob from the inside part of the digital lock. But anyway the lock will auto unlock before it gets burn to chao da.
The fire sensor only detects temperature from the inside, not outside.
a) Not all the locks I've seen have a knob on the inside. There is no guarantee the knob won't seize when the electronics has failed. Does the mechanical portion include a deadbolt?
b) A lock that auto-unlocks can be considered to have an inherent weakness.
Heat sensor is on the inside? Am not an experienced burglar, but I would think a portable drill with a 1" wood drill bit (unless you have a solid steel door?), a bit of preformed metal tubing to re-direct the flame/heat, and a butane blowtorch are probably all the tools one needs to defeat these locks in under 3 minutes. Possibly sooner if they're experienced, and are very familiar with the particular lock you have installed (eg: the exact location of the heat sensor, and the temperature it needs to trigger...)
Am still not convinced that the convenience they provide is a fair trade for their apparent lack of security.