I can do a few different mods here. The easy: LED single color any where on the console, or a color changing LED, like this one.
$5 for single color LED.
$7 for color changing LED.
In order to play Japanese games you have to have a converter, sometimes you can find them on ebay, but not cheap.
OR, you can have the converter built in and change between US and JP with the flip of a switch.
If your system won’t power on and you’re sure the a/c adapter is good then the internal fuse could be blown, easy fix.
CD-ROM broken, no spin, no audio etc:
There are a few reasons why the DUO CD wont work properly. The console may have some capacitors that have failed, the laser itself may have failed, or a mechanical failure (limit switches and gears).
The cap problem seems to plague all DUO consoles so it will eventually need them all replaced even if that’s not the main problem.
A new laser is easy to replace, but somewhat difficult to dial in:
$30 if you supply a new laser, $60 if I supply the laser.
Mechanical will have to be diagnosed and quoted on a case by case basis.