UPDATED Summer 2020: As of Android version 3.6, the Alpha or Numeric keyboard setting is now found within the Settings area of the app. Click the “Setting Gear” ⚙ icon to reveal this setting.
For versions prior to 3.6, to enable numeric (or alpha) keyboard input into the VIN/Unit Number field on Android, CLICK THE LOGO on that screen.
This will enable a settings screen, which allows you to toggle the setting.
After version 3.6 we use a more conventional “Setting Gear” ⚙ icon which you can click to reveal this setting.