If your Backtrack appears frozen or if the LED lights are blinking in a series of colors then performing a hard reset should resolve this.
To perform a hard reset you'll need to manually press a small object like a paper clip into the small hole on the side of the Backtrack. The hole is located on the opposite side of all the UI controls (Backtrack) or on the side opposite the microphone (Backtrack + Mic).
Hold the button down for three seconds and then remove the paperclip. The LED on the device will glow white, blink a few times, and then begin blinking blue.
If this does not help, please return the backtrack to your dealer.