Ring Pro issue

Hi, I would like to ask about a Ring Door Bell Pro, I get one 2nd hand, everything it’s installed by a professional but it still not working. There’s a power on it but it keeps flashing blue. I tried factory reset but still I’m enable to put it in a pair mode, when I pressed side button nothing happens…Anyone can help?
Thank you

Hi @user2047. I suggest reaching out to our support team. When buying secondhand, there is no way to tell if the device is defective or not. I suggest only buying from authorized retail partners to eliminate this in the future. Please give our support team a call at one of the numbers available here. If you are outside of the US, please visit here to see how to contact support.