Mystery issue (Yaris T-Sport)

Hi everyone,

[My 2003 Yaris T-Sport](https://imgur.com/a/rBE5X4n) (Phase 2) is driving me crazy: [the odometer only shows "0"](https://imgur.com/a/zZajrxO) and now it can't pass the technical inspection, even though everything else is working perfectly. The speedometer, tachometer, and trip computer all work fine, so the data is definitely being read by the speed sensor... but the odometer just stays stuck at 0.

The issue started after several months without driving: the battery was flat, so my uncle used an old battery charger from the 80s, and when I started the car the odometer was dead.

Here’s what I’ve tried so far, with no success:

- Replaced the small LCD screen where the mileage is displayed

- Replaced the entire instrument cluster

- Replaced the odo/trip button, which apparently can act as a fuse in cases of electrical overload

The Toyota dealerships I've been to have no idea what it could be. The last one just gave me [the car’s wiring diagram](https://imgur.com/a/TrZbHLf) and wished me luck, but I’m completely out of ideas now.

Has anyone seen this type of issue on a Yaris T-Sport or any other Toyota? At this point, I’ll take any theory, no matter how crazy it sounds—I just want my beloved car back on the road!