Try to use the app on another device to see if the issue persists. If it does, then the culprit is most likely the controller on the rower.
First replace the battery in the controller, the battery is a CR 2032.
If you have just received the rower and your resistance is not changing, please be sure to check the back of the handlebar to remove the white tag and enable resistance.
If resistance is still not working, then try the steps below to re-pair the controller:
If you are still having issues with the resistance on the rower, the controller for the rower would need to be replaced. please contact firstname.lastname@example.org