For your BeoPlay A2 you should use a mini-USB cable (the same kind of cable used for many digital cameras). For other products, you should use a micro-USB cable (the same kind of cable used for many Android smartphones). Some cables do not have the necessary data wires and can only be used for charging. If the software update gets stuck at the "Assessing device" step you may have such a cable. You should instead get a cable that supports data transfer.
