My second (replacement set) of Niteflux Photon Max LEDs failed last night.

I didn't get anywhere with Niteflux when my first set went, so I won't even bother this time.

The battery won't charge, I've tried two Niteflux chargers and the light on the battery doesn't come on at all.
I need a replacement battery, the only problem is the Niteflux battery had the only switch built into it?
The spec is 4 cell Li-ion 16.8V 2200mAH
Any ideas or should I give up. My old Lumi halogens are still going as is my ancient Joystick.