Ring Pro keeps losing power

Hi, I received and installed the Ring Pro and plug in adapter last week. I've installed it but it only seems to last 36 to 48 hours before powering down completely. I've tried different power points and checked the connections at the back but no joy. The app says the 'last reported voltage is good'. It charges / powers up fine initially (takes about an hour each time) but then just seems to run down after that... when it runs down, if I turn the power off and on again, it slowly powers up /charges up and then works fine again for a day or so. Is there a fault here or something else I need to do?