The you should never have run opkg to try to upgrade it, eh?
What's stopping you? Use of skills in reading and comprehending directions before taking action. Over-reliance on these forums to spoon-feed you personalized directions.
Right now, what you are trying to do is well past your apparent understanding of Linux-based OSes in general, and OpenWrt in specific.
I think you would be greatly benefited by purchasing a well-supported device with a relatively fool-proof recovery method. I recommend something like the GL.iNet AR300M-Lite, which is now supported in snapshots[1]. That device has a very good U-Boot, for which GL.iNet has included a web-based method for flashing an image, without use of serial. It is available for under US$20.
Use of such a device will let you better understand how to manage and troubleshoot an OpenWrt system.
While not quite a "12 o'clock flasher", you should stay out of editing config files, configure only using LuCI, and never write to the raw MTD devices.
You should also plan what you what to accomplish. That you're fixated on connecting via ssh to a device that you have serial access to is puzzling. One with sufficient skill should be able to ssh/scp from the device to any other connected device, without needing an SSH server running on the device.
[1] The AR300M-Lite should generally not be flashed with the AR300M (no -Lite) firmware that has been available for some time now. As the AR300M-Lite has a single Ethernet port and the "no -Lite" version has two, the AR300M firmware on a -Lite version will, on first boot or reset to defaults, likely be unreachable. This can be recovered by flashing the proper firmware version through U-Boot over its web-based interface.
So I've basically managed to get as far a the password prompt in ssh, but whatever password I use, or change via passwd in the serial console has no effect.
your device operating system is not an official openwrt release. therefore, the help you are receiving here is complimentary. show us you deserved it and go and find a source of information ( preferrably not a forum ) and study, who made the OS, and how they setup the users / login.
or, get some nice linux books.... use that system to learn.... what a great opportunity!
It's an Orthodox File Manager...based on look/feel of Norton Commander...one of the first prototypes (not made by the company who made the OS) - for almost all GUI panel-based file managers known today.
I should note it also accepts mouse movements - which means it possesses a Graphical User Interface by definition. Until you made the statement above, I've never heard anyone make such a distinction outside of educational circles.
I should also note that the development of GUIs was exactly because of the reason you stated:
So, @jeff's point was misunderstood. You should truly get a grasp of the underlying software. You'll need to when you encounter a device that doesn't have capability/space for the installation of mc. You may have found your reckoning on that issue in the GoFlex Net.