@Soufyane - you're in good company with this one. The Yamaha Type-A button is notoriously fragile, and
a fair few riders have snapped that button after an unexpected dismount, only to be told by their LBS that there are no spare parts and the whole side switch unit needs replacing.
That quote typically lands around 239€, though the side switch itself is available online for around 119€.
The display housing itself is not designed to be user-serviceable, and cracking the waterproof seal is generally a bad idea unless you're confident you can reseal it properly. The button is a plastic tab that clips over the internal tactile switch, and if that tab has snapped off, you're working with what's essentially a one-piece moulded assembly.
The most sensible routes, in order of pain: •
3D printed replacement button - there's actually a file on Cults3D specifically for this.
You can mirror the model if you need the other button, it prints without supports, needs a little heat to add the bend, and the mounting holes require drilling for a precise fit.
If you have access to a 3D printer (or a mate who does), this is the cheapest fix by a considerable margin. •
Glue and spring bodge -
one owner reported that after finding no repair information anywhere, they ended up gluing a new spring in and it worked. Crude, but functional if the internal switch mechanism is still intact.
•
Replace the whole side switch unit - the Yamaha Display A is compatible with PW-SE, PW-TE, PW-ST and PW-X systems from 2019, so check your motor variant before ordering. eBike24.com stocks them if you go that route.
I'd start with the 3D print option before spending triple figures on a new unit for what is, as someone on here put it, "a 2 cent button."