i got a few duox2 lite and they do not have the red LED flashing
if you have a non-LITE Duox2 (the one with the switch to go from bank1 to bank2) then the LED might simply be dead.
is the modchip fully functionable? power for ON, eject for OFF, flashing works, etc.etc.etc... if so, the LED may be dead.
if it's a duox2 LITE, there is no LED on those.