The joyn app won't start. What should I do? Laura L. Updated March 20, 2017 13:42 Follow Please do the following steps: Remove the joyn app from your iPad Open App Catalog. Re-install the joyn app. Related articles Does the joyn app function on an Android tablet as well? How do I re-install the joyn app? My customers are no longer able to scan. What should I do? Help! I've accidentally removed the joyn app from the iPad. How can I reinstall it? The Joyn Retail app requires my security code for each transaction. Can I disable this? Comments 0 comments Article is closed for comments.