Reviving a dead thread!
The replacement battery pack has been working just fine, but yesterday, the light refused to turn on. After my ride, I charged the pack and did some testing in the garage. The indicator light on top comes on when I hold the power button and will toggle properly between green and green/red if I hit the button to change modes, but the lamp itself never comes on in either high or low mode. I've had this light since 2008, so is it safe to assume it's reached the end of its illustrious career?