TN42 Troubleshooting Help?

I posted a while back about needing a new battery carrier after putting a battery in backwards and, basically, melting two of the negative wires. I soldered two new springs on and measured 8.1 volts on the carrier. When in the light only the switch light comes on. I waited until I got the new carrier and the same thing. Different batteries makes no difference and using those batteries in a Sofirn Q8 work fine. I get 8.1 volts across the red and black at the LED. When I turn the switch on I get 8.1 across the black and white. It’s as if the LED has stopped working.

Any thoughts on an easy fix? It’s seen very little use and is only a couple years old.