Do you mean it keeps cutting out, turning it's self off and on? if so then remove the box from power supply and open box and have a look at the connection inside (from on/off switch to circuit board). There is a white plastic "plug and socket" that links on/off switch to the circuit board inside box, it's on the back/left side as you look at box, just make sure that it is securely pushed home, maybe that is your problem.
