Went through as instructed. Bluetooth seeings screen on phone set at 'scan for devices'. Pressed both 'rev' and 'power' buttons. Amp displays 'Bluetooth pairing enabled' followed by a 10 digit pairing code. But my phone simply won't find the amp. The phone is a Sony ZX1 with latest Oreo software.

Tried the same process with my wife's handset which is a Samsung galaxy 5.

No amp is found on that device either with the same process. 

Not sure what's left to try  

Any advice