Lightship Enterprises is still in business. They are leaving the retail market, but still are making lighting products. I believe that would include their flashlight line. I own an M60L. Surefire batteries do not work real well in my M60L as they do not make real good contact. I have had to fiddle with almost evey set of Surefire batteries that I have tried before they would work well in several different lights that I own. The M60L did come with Powerizer batteries. I have found the Titanium brand batteries from AmondoTech to be very good. They have worked better for me then Surefire or Powerizer and are cheaper too. They also have a new battery, I have not tried it yet, that is supposed to be designed for flashlights.
The problem with the Surefire batteries I have owned is that they do not make real good contact inside the flashlight. In one case a small hair was keeping the + and - between the batteries from making proper contact (new battery right out of the box). As mentioned before, I have found this contact problem to be true with my Surefire batteries in other flashlights also.
Amondotech CR123A page
At this point it may still be a battery issue. If you try the Titanium batteries and you still have problems you could email Lightship Enterprises, but your vendor should be willing to take care of it if you just purchased the light.
NightCutter
In the short term, you may want to take the batteries out and clean the + and - contacts and look for anything that could be compromising their connection on the batteries. If new batteries do not work there may be a problem with the voltage control circuitry.
One last point, do not put RCR123A's or LIR123A's into this light. Lightship Enterprises says the light was designed around a 6 volt input and higher voltages can damage the circuit.
I have had email corespndance with Lightship Enterprises very recently on an unrelated matter (reghargeable battery questions--answer mentioned above). They are generally very good about returning emails. Just let them know you are a product owner needing some help with your M60L in the title.