What power adapter do you use ? You need at least 5 Volts 1 Ampere. Depending on the connected peripherals it is possible that you need more than 1 Ampere. I think they advice 1.5 A and 5V for the adapter if you connect USB things. Maybe your USB Stick needs too much power. I am really sure that this is the problem for you. The mini wants more power than your supply can deliver and then it shuts down.