I pulled out my RCT715 to recharge it, and when I connected it to a charging device with a USB-A to USB-C cable, it just showed a solid color instead of a flashing color. I'm one of those lucky Caucasians with Red / Green color blindness, so I'm hesitant to say what color I saw. (So many electronics use red and green lights to indicate charging status or charge level, and when I mention that 8 - 15% of Caucasian males have Red / Green colorblindness, they act as if they've never heard of it!)
Anyway, I then connected it using a full USB-C cable (the one from my Edge 1050), and it charged up fully, while showing a flashing light.
I thought the USB-A to USB-C cable I originally used was the one that came with the RCT715. The box it came in is empty of any equipment, and the cable I originally tried was plugged into my Anker Prime wall charger, with three USB-C ports and one USB-A port. Now I'm not so sure, and the garmin.com web site just says "charging cable" in the RCT715's description. Can you tell me which type of cable came with the unit?