Most automatic litter box sensor errors are dust and fur on the sensors, not a dead unit. Symptom-by-symptom fixes, in the order worth checking.
Smart Litter Box App Notifications: Keep 2, Silence Rest
After five years with three cats, here are the only litter box app alerts I keep on, the ones I silenced, and the one you will miss if you mute all.
Litter Box Weight Tracking: What It’s Good For
Product pages say the scale detects disease. It does not. It measures mass over time, and a trend is a reason to look, a vet decides what you are looking at.