Problem
If you encounter an error while activating your Samsung Galaxy Watch, please touch the Device Info button on the error message screen to display the corresponding error code. Once you have the code, please follow the subsequent steps below to resolve the issue.
Error Code 4001: Grant Permission
The Carrier Login Engine app must be granted permission to access the Phone functions.
Step 1: Go to Apps > Settings > Apps > More Options menu.
Step 2: Touch Show system apps > Permissions.
Step 3: Touch the slider to turn the permission on.
Step 4: Once the SIM card has been inserted, restart the phone and ensure that it is connected to a mobile network.
Error Code 4002: Update Software
Verify that the latest updates for both the phone and Galaxy Wearable app have been installed.
Step 1: Go to Apps > Play Store > Menu > My apps & games.
Step 2: Touch UPDATE ALL to update all apps.
Note
Galaxy watch is currently supported by AT&T, Sprint, T-Mobile and Verizon.
Source
Samsung Troubleshooting Guide: Galaxy Watch Activation Errors
