just found your message here as well, so my reply is the same like in my email and on facebook. Therefore, it does not contain any news for you, but maybe for others with the same issue:
As far far as I understood, you tried to update Max2Play in the „Advanced Setup“ tab which is only available for Max2Play for ODROID. There is a warning below the update button saying you should not update if your U3 image is not based on Ubuntu 14. I tried this update feature with a new U3 image based on Ubuntu 14 and everything is working normally.
I recommend to download the latest image for the U3 on our homepage, burn it onto your microSD card or eMMC module (in combination with a microSD adapter) with the program Win32DiskImager. After you have started your U3 successfully, enter the Settings/Reboot tab, do an update to version 2.26, expand the filesystem, activate the „Advanced Setup“ plug-in and check for updates there afterwards.
Maximilian from Max2Play