Finally fixed the Duo R, turns out at some point too much force had been used when plugging in the cable and the top part of the green pin had been bent upwards, after bending that pin back down it works fine now.
Anyway, now I can finally ask a question about games. I keep on seeing sealed copies of CD games listed on eBay for the same price as used copies, are they likely to be genuine or is there a problem with repros/bootlegs in the PC Engine scene (as there is with Mega Drive)? Some are obviously old copies, but a few look like they're just out of a factory (eg. this one).
It's hard to tell when it's still shrink wrapped. I would say it's an original. The game is not super rare or expensive so I doubt they would bootleg it.
EDIT
wow that seller has a lot of sealed stuff for sale!