Flashing file folder with question mark- will not reboot in recovery mode
I erased my iMac for trade in or recycle. Now it has a flashing file folder with question mark and will not reboot in recovery mode. Would like to schedule an appointment at Genius Bar because I live 3 hours away from the closest Apple Store. Tomorrow I am traveling to a location that has an Apple Store. The Apple Website continues to prompt me to repair this issue myself. I am not having any luck. Please help.
iMac Pro