My G5 with phase 2 does not display the "C" at anytime. I have plugged it into the USB to charge and used the drop in charger.
One thing I have noticed though is there are some 'icons' that are supposed to show up at various times and they don't. They are not (at least to me) show stoppers so I have ignored them though I did report them to Unication when I first got my G5.
I don't even recall what they are now and I'd have to find the 'brochure' to see which ones don't appear. I think one was when connected to USB, but don't hold my feet to the fire on it.
The amplified charger icon is a solid yellow. The desktop charger icon is a white outline with a blue-green filler. I assume the firmware detects which charger is in use...but why? Maybe the unit needs to know whether to send signals to the amp, relay, ext. speaker port, etc. and the icon is an indicator that’s happening?