My DRE-6000 ENR headset no longer functions in "active noise
reduction" mode. It may have suffered a voltage spike when I was
using the "auxiliary power" outlet in the Cutlass that I rent. The
headset itself might be OK; I'm wondering if the battery/power unit
took the hit. The headset still works in "passive" mode. The power
unit just won't turn on (it shows an OK status when I press the
ON/Test button, but doesn't stay on). Any recommendations on a shop
that might be able to repair it?