Clear Your Android Device’s Bluetooth Cache
Removing your Android device’s cache files may help fix disconnection issues. This is harmless both to your device and to your Square Contactless + Chip Reader. Removing cache files is not possible on iOS devices. To clear your cache:
Go to the Settings on your Android device.
Click ⋮ to display your system apps.
Select Bluetooth from the list of apps, then select Storage.
Tap Clear Cache and exit your Settings.
Restart your device and try repairing it to your Reader again.
If the steps are a bit different on your particular Android device, you may want to search how to clear the Bluetooth cache for your specific Android Device.