You can force the internal software update from the Withings App.
Go to Devices > Body + > All settings > About and tap Check for updates.
Follow the instructions on the screen to go through with the internal software update.
https://support.withings.com/hc/en-us/sections/4411046153745-Body
https://support.withings.com/hc/en-us/sections/204132387-Maintenance