I've had a few odd problems over the years. More info could be helpful here. Brand of unit, happen when you hit a bump or any other variables, etc. Any other notable noise issues or anything?
Right off the bat, nothing really points to installer error given your description of bluetooth/radio input operations, though a weak connection somewhere external could be present. Have had seemingly radio only power loss after hitting bumps in road, which finally turned out to be battery going bad, shorting out. Positive connections, including yellow memory wire, are just as suspect as grounds. Amp wouldn't work ever if blown fuse, but blue remote turn on wire signal from unit would shut it off. You would have no lit power indicator on amp if remote signal was lost. Is you amp for full range sound , bass only , or both?
Would you possibly have access to another head unit to try out? Have run into more than one of the same product model of items having same #*#^##! issues.
