This is a demo. It is the real settings page from the clock's Wi-Fi module, running against a simulated clock. The time, temperature and supply voltage are invented, and nothing you change here is saved or sent anywhere. Reload to start over.
— you have
The clock goes dark for a few minutes while it writes its own flash. It cannot be left half-done: if the power fails part-way, it restarts waiting for the firmware and you can send it again.
Press and hold the top-right key on the clock. Keep it held for two seconds. Nothing is written until you do — this is the step that makes an update something nobody can start from somewhere else.
The serial identifies this clock to the update server. It is written once and cannot be changed afterwards — a clock with the wrong one is told it is up to date forever, and says nothing about it. Check it before you save.