The bike is partially still rideable but has Error 44 and is permanently stuck in 4th gear. In the meantime, the boost button has failed (likely a broken solder joint or similar). It is still usable with some effort, as it continues to provide assistance. Here are a few more details:

- Battery is in good to very good condition
- Total mileage approx. 10,600 km
- Ceramic brake pads, brakes need to be bled
- Schwalbe Marathon E-Plus tires (puncture-proof) retrofitted
- Chain has already been replaced once
- Saddle cover is damaged in one spot
- Mudguard shows signs of rust
- Right brake lever h...