Make sure that the Bluetooth pairing mode is turned on.
Restart the watch and search for the watch again.
Make sure that the watch and the other Bluetooth device are within the support Bluetooth connection range (10 m). The distance may vary depending on the environment the devices are used in.
When pairing with an iOS/Android phone, make sure that the device has been removed from the last device's list of paired devices. If it was paired before, make sure it is also removed from the PLAYFIT App, then go to Settings > Bluetooth, touch the Settings icon behind the Bluetooth name, and touch Forget This Device. Then, pair them to connect the devices again.