Anyway, if it can be of any help, I did manage to uninstall the pre-installed 14.1 version of kodi and install 16.1 jarvis without rooting the device. I can't say that it made any difference in terms of speed, but at least the codec support is fully functional without the need of third party addons.
Can you make a guide on how to get Kodi 16?
Without codecs to play local files this box is useless to me 
- First download and install confluence++ skin for helix and apply it.
- From the home menu go to android apps.
- Go to play store. There you can login with your google account and download apps just like on your smartphone or tablet.
- Download any third party launcher (apex launcher would do fine).
- Press the home button on the remote. A pop up menu will appear asking which launcher you would like to start (XBMC Start or the third party launcher you installed). Select the third party launcher.
- From the launcher go to system settings, select apps, kodi and uninstall it.
- Go to play store, search for kodi, install it and you' re good to go.
P.S.
1) Do the above procedure at your own risk, as I read here at the forum that doing so may brick your unit. It worked for me though.
2) As I wrote above I did this procedure without rooting the device. It worked for me but from what I read here at the forum others cannot uninstall kodi at all. This means the device must be rooted first. Again if you decide to do so, do it at your own risk as rooting an android device may not have always the same result. It may brick the unit.
