Installed Android Pay app on my new BV6000 but get error "Google is unable to verify device or software is Android compatible". This message usually associated with rooted devices - but BV6000 I understand is not rooted. Any help much appreciated.

Some supplyer install own software so some apps might think the phone is rooted.
Also the ROM labelling as "Test-Keys" which should be "Release-Keys" in Build Tag might lead to apps behaving like this.
To ensure it's not rooted install an app like "Root Checker" which specifically look for the su binary.