Firmware update through OneSync is stuck or never finishes

Symptom. You launched a firmware update from OneSync and the progress bar has not moved for a long time, or OneSync closed during the update and the device no longer responds normally.

Before anything. Never unplug the device during an active update. Give the update at least 30 minutes before intervening.

Steps. 1) Verify you are running the latest OneSync version from hexoskin.com; older versions contain update bugs. 2) Close OneSync completely. 3) Power cycle the device (press and release the button; avoid holding it 2 seconds, which enters debug mode). 4) Reconnect the device by USB directly to the computer (no hub). 5) Relaunch OneSync and restart the firmware update. 6) If the update completes but the device behaves abnormally, do a Factory Reset from OneSync and re-pair in the app.

If the device no longer boots. Stop and contact support with the device serial number and the OneSync version. A recovery procedure exists and the device is usually not lost. Do not retry repeated updates on a device that does not boot.