Contact Xiaomi support and they should be able to send you a new one just be honest and explain the issue. That's what they did for me when my Mi Box stopped working
May have to factory reset, unplug it, hold down the back and select button and plug it in. Might take a few tries. Should be able to factory reset from that menu
Touch the top of the box and see if it's burning hot. That was the cause of most of my issues on long streams.
the same thing happened to me with my Shield Tv and a factory reset thru fast boot mode. I got this from the MIbox forum hope it helps...recovery mode is entered by rebooting the box while pressing the home & option button on the remote. keep these pressed until the first screen disappears. you should get into recovery mode For the mibox pro, the options are limited to wipe data & reboot with another rom. i haven't been able to install update.zip from recovery mode.
I've Tried Unplugging The Power Adapter As Well As The HDMI and even reset the tv...still No luck. Any help?