I purchased a Hero3+ silver. I downloaded the mobile app to my Samsung S6. Per the instructions the password to use is: "goprohero". The mobile app gives a message that the passoword is incorrect or may have changed it from another device.
I never have owned a GoPro before.
Please proceed with a WI-Fi and a firmware update.
Make sure to save the UPDATE folder to the root of the SD card.
Once the update is completed, try the pairing process again.
Let us know how it goes.
You may also reach out to our Support Team through https://gopro.com/help/ContactUs for further assistance.