What to do if you can't open the Battle.net desktop app, and there are no error messages when you try.
How to obtain error logs for Blizzard games
Troubleshooting steps for this error in Diablo III
Troubleshooting steps to help you connect to Diablo III
Attempting to play Diablo III results in error 3007 or 316704
Troubleshooting steps when you can log into your account management page but not the Battle.net App
Blizzard Customer Support cannot lock your account on request