This fully working tracker has a new battery installed but comes with functionality limitations.

It was sitting in a box and missed the opportunity to be upgraded to the latest firmware, so now it will remain on the 6.46 version partially supported by the Fitbit app:

Mobile Fitbit app (iPhone and Android) - data sync and upgrade are not working even after linking it to the app.

PC Fitbit app (tested on Windows) - data sync works but upgrade fails. just skip the upgrade during the setup.

The only reason to connect it to the Mobile Fitbit app is to set up/sync time on your tracker.

Don't try to update/upgrade it via any app - it will fail, and there is no workaround.

What works:

• It counts steps, distance, floors, and calories. Shows time.
• The battery holds for more than a week.

What doesn't work:

• Sync data to the Fitbit phone app.
• Firmware update/upgrade