Firmware Update Fails

[robert-hh]

The updater uses USB for transferring the image. If you already had a REPL prompt though USB with simple tools like screen or picocom, the connection part should be OK.
If not,

• check the cable, the access rights (UDEV rules).
  In any case:
• did you connect G23 and GND and pus reset afterwards?
• check whether your PC has access to the Internet, because the image is retrieved on-the-fly during update.
• try to reduce the speed.