Error 19 indicates an internal communication issue with the battery.
Try these steps to fix it:
1. Make sure your bike has the latest firmware installed – you can check this on your app settings screen. If there is a new version available, install it.
2. Press and hold the power button on the underside of the top tube for two seconds until you see the reset symbol on the Matrix Display. Your bike will now restart.
3. Press either handlebar button to power the bike on. If the bike is locked, use one of the 3 ways to unlock your bike.