I had a patron come in with a problem with her Overdrive on her iPad. She was stuck in the 'authorize this device' step. She's put in her e-mail address and password, but the 'Authorize' button was greyed out. We couldn't back out into the Overdrive homepage. Even when we closed Overdrive and reopened it, we were stuck in the authorize menu with the button still greyed out.
After restarting her iPad, it reset Overdrive, letting us finish authorizing her device.
From there, I also walked her through how to download an e-book both through Overdrive and through her Kindle App.