Confirm you haven't skipped Step 3 of the update process.
If you have an Ethernet connection, please disconnect it and try again.
After Step 3, please allow a few minutes for your Mac/PC to establish a stable connection with NM2 and try pressing "Go to Updater" again.
The upload bar may hang at 100% and return an "error" message. As long as your NM2 resets at 100% the update was successful.
If the upload fails prior to hitting 100%, please try again.