It would be difficult to blow up the neutral light, but having said that, here are a few things you can check.
The neutral indicator in the stock speedo is powered by the ignition fuse which is hard wired to the positive side of the neutral LED indicator. To complete the circuit, the negative side of the LED passes thru the neutral switch to ground thus completing the circuit. To manually light the LED, there is a light blue wire with white connector under the seat on the right hand side, this is the wire that goes to the neutral switch to ground, and incidently the same wire we tap into for the DG8 gear indicator. If you pop that off and short to ground, that would test to see if your stock speedo still works (ignition on but not running of course). If this works, then you have a neutral switch problem.
If is still does not work, then check to see if your meter lights are illuminated as they are on the same circuit as the neutral indicator. If not, the wire from the fuse to the speedo connector is messed up. You need to trouble shoot that.
If the meter lights are illuminated, then somehow the red/white wire has been separated from the red/yellow wire.
What have you found?