If the watch froze, went white or stopped responding while you were coding on it, the good news is that this is almost always the program rather than the watch — and it is reversible at home.
Restore the stock firmware
Connect the watch to a desktop computer running Chrome, Edge or Opera with its USB cable.
Open code.circuitmess.com and use the Restore firmware button. This wipes the custom code and puts the watch back exactly as it shipped.
If the computer does not see the watch, charge it for an hour first, try a different USB port, and check the cable is a data cable — the checks are in My computer doesn't recognise the device when I plug it in. What's wrong?.
If the restore stops with an error such as "MD5 of file does not match data in flash", the firmware did not write correctly, which is usually down to the connection. Use a different USB data cable, plug it straight into the computer rather than into a hub or adapter, and run Restore firmware at code.circuitmess.com again in Chrome, Edge or Opera. The full checklist is in The firmware restore at code.circuitmess.com fails or cannot find my device. If the same error comes back, message us here with your order number, a screenshot of the error, and the computer and browser you used.
Your code is not lost. Sketches are saved in your CircuitBlocks account, not on the watch, so after a restore you can open the sketch, fix the loop or bug that locked it up, and run it again. Why programs behave this way is covered in Why doesn’t the program I wrote in CircuitBlocks stay on the device after a reset?.
If the watch stays frozen even after a successful restore, or it froze without any coding involved, treat it as a hardware question and see Something is wrong with my Artemis Watch 2.0 — that article covers what to send us.