You can always open the Bang & Olufsen app again and follow the steps to resume the software update from where you have stopped.
How do I update my Beocom EX with the latest software?
Note: Please do not close the app while updating your earphones and remember to have your mobile device and earphones placed in the charging case with open lid close to each other. The light indicator will pulse green on the charging case while the update is in progress.
When the update is done, it will take approximately 30 seconds for the earphones to reboot. When the light indicator turns solid green your Beocom EX have been updated and are ready for use.