We are using CINCH with our Raspberry Pi 2 because we had trouble connecting the standard way. Now, when I connect to the dex wifi network, I can access VNC and Scratch, however, we cannot update Scratch or do some of the commands because we are no longer connected to our home wifi network.
Also, the connection to the dex wifi with CINCH only works for us when the GoPiGo is plugged in to an outlet - not on battery power. when we connect battery power (with fresh batteries) it loses the dex wifi. This is also making it hard to play with the robot when it has to stay 3 feet from an outlet.
You are absolutely right, when using Cinch you lose the ability of upgrading your card. There’s a workaround for that and it’s described here: http://www.dexterindustries.com/howto/use-cinch-operating-system/#update
In summary, you have two options, either connect to a physical router for the duration of the update, or share your computer’s internet connection.
As for the batteries connection, what exactly happens when you switch to batteries? Does the green light next to the power switch (on the red board) stay on? Do you see it flicker? Do you still see a red light on the belly of the Raspberry Pi? (there’s a green light there too which may flicker, that would be normal)