I doubt that there is anything wrong with your Bartok. It may just be an incompatible drive but I can’t tell from your answer.
The light not switching on doesn’t necessarily mean that there is no power but that there is insufficient power. As I mentioned the USB2 input is only designed for low power draw. As you mentioned a cable being involved I am guessing that your USB drive is accordingly not a flash drive. As it isn’t self powered I presume you are using a 2.5" external HDD.
The USB A type input on most ( all?) current dCS DACS is really only meant for flash drives and is regarded as a convenience feature for the occasion when a friend brings round some tracks. More regular USB replay would use the USB B type input, for example replay from a computer.
Have you got a normal flash drive to try?