For now, you can download the XRP Controller firmware from here: Releases · sparkfun/micropython · GitHub
Go to the latest release, find the file for your XRP Controller (either beta or not), download it, and flash it to your board.
Eventually, you’ll be able to download the latest firmware from here: MicroPython - Python for microcontrollers Right now there are preview builds that are missing some upcoming features of MicroPython v1.25, but once that releases, I’d suggest downloading the firmware from the MicroPython downloads page if you need.
Although ideally, you should not have to manually flash the firmware if you’re using XRPCode, it should handle it for you. I only suggest these steps if you need to do so for some other reason.
Hope this helps!