Hi, I sold to my friends, about 5 discolasers of 30mw (50mw one) and a unit, same thing happened.
I guess that is a bad connection or bad solder the diode. You can remove and check the solder points.
After nearly a year, lithium battery, I can say the following:
30mw Discolaser: accept a lithium battery (10,440 to 3.7 v), 15% or 20% more powerful and more consistent. Use a conductor (copper wire, a pencil stub.) RECOMMENDED.
I pobado long time and many times and still like new.
50mw Discolaser: NOT accept lithium battery (10,440 to 3.7 v). I tried it and the diode is burned.