How can I change firmware on URC-TW2 (custom Vera Edge) to factory Vera Edge firmware?

I’ve been using a URC-TW2 which is a Vera Edge with custom firmware for URC.

How can I completely wipe the firmware and switch to factory Vera Edge firmware?

In the web interface I can specify a custom firmware url and I tried this:
http://builder1204.mios.com/mt7620a_betafirmware/mt7620a_Luup_ui7-1.7.1248-en-mios.squashfs

…and it appears to be successful but it comes back to the URC branded interface.