I may have been making it more complicated than it needed to be.
I factory reset, I put games all back on. The games were on there and it worked. FDS works by default with nes classic, that's great!
Can someone please tell me how to get the games working that hakchi tells you won't work with default emulator but should work with other emulators?
This time, after a factory reset, all I did was install the latest retroarch neo 1.7.4, and a single core module, mesen.. In trying it, I can't tell if this actually did anything. These are installed according to hakchi, but when running nes classic, it shows no evidence of it, and the games in question still don't work.. I uninstalled the mesen module and instead tried nestopia (which seemed to me to imply it auto boots from selecting a game or something). Still no evidence of anything.
To recap, I just want to do the simple thing of getting the games that don't work in the default emulator, to work. All videos and tutorials are referencing older versions of hakchi, older versions of retroarch... but it appears it should be as easy as installing retroarch and an nes module. Well I did that, but I'm still getting the c6 error on the games in question.
I'd really appreciate the help. This is a gift for my brother for christmas, and I had hoped to solve what seems like ought to be a simple issue. You would save christmas if you could give me a bit of a hand here.