Hi ...
I bought a DIN powered USB socket and after plugging it in to accessory power socket - it worked fine.
Connected my phone - it was charging fine.
Went for a ride - phone had lost power and was discharged.
Subsequently removed the plug - re-connected - nothing.
I've learned there are no fuses - so curious what's caused this.
There are no fuses on your bike, correct, the bike's electronics senses over-current in the various circuits and electronically cuts power when it senses what to it is a fault condition. Normally when you remove the offending device or correct the fault things should return to normal, as the electronic "fuse" resets itelf.
When you plug other gadjets into the DIN accessory socket do you get power ok? Could be that the accessory you plugged in has gone faulty or draws too much current with the phone attached (which would be very suprising).
I take it your phone is charging up OK elsewhere and holding it's charge as expected?
My money is on the phone charger being faulty...