If a reset (the reset button is in the audio jack, push it down with a toothpic or something similar and plug in the device at the same time. I avoided using anything metal, such as a paperclip, not sure if that matters). It will delete the XBMC off the device and factory reset it. Boot it back up, then go through the startup if it has you do one. Setup your network. Then go to SettingsMBox app>advanced>Remote control to ON in order to use the RemoteIME app. To reinstall the version of XBMC it came with, go to OTA Updater app, XBMC is automatically populated in the list across the bottom (must be popular). This installs the version that came on the box. You are also able to install another version if you prefer it, just load it to a USB drive or SD card and plug in, and install using AppInstaller.
I hope this answered some of the questions posted.
For the person with the hardware problem, Matricom is great about return/replacement, there's always a chance, with any product, to get a dud, so if your issue is hardware then by all means reach out to them, the warranty is 1 year.
I have been using their original box for a while and just updated to the newer box, it works a lot better and was preset with all this, versus the hassle of flashing that you had to do to the original box. Remote works better, also, though I use the app on my phone most the time.
I don't work for them, though, so I can't offer more support than what I learned through personal use.