Chromecast’s reset button is a test of hardware reliability in a digital world.

Google’s Chromecast is the epitome of a first software device. Almost all of its capabilities are defined by the software, and generally not even the software that is in the Chromecast.

But the Chromecast, despite its simple simplicity, has a single hardware button: an emergency reset button on the back. It is a testament to the importance and reliability of physical inputs on software solutions.

Most people will most likely never use the Chromecast reset button. Whether you have the original Chromecast, a second-generation model, or an Ultra 4K Chromecast, this button has only one function: if everything else fails, you can press and hold to reset the factory hardware to “fresh out of the box” ”

(The process is really interesting: pressing the button forces Chromecast to start in a USB boot mode, where it searches for a local copy of a signed system image and loads it. Enterprising users have tried using this mechanism to load their own software also on Chromecasts!)

You can’t lightly press a button: Google warns in bold on its support page that “This action will erase your data and cannot be undone.” It’s just the kind of thing you would use if you’re selling your hardware or running into problems so deep that the only solution is a clean whiteboard. Even activating it requires more attention than a simple reboot, asking users to hold down the little oval button on the back long enough to make sure they really want to do this.

But it’s not the button mechanism itself or the physical hardware (not a particularly exciting button) that is fascinating about the Chromecast reset button. It is even a button at all.

Google’s Chromecast is one of the simplest plug-and-play devices out there. You take it out of the box, connect it to power and an HDMI port, and voila. There is no remote control or even a power button. You just plug it in and it works without any user intervention. Then you need another device to control everything about Chromecast, from settings to what you want to stream.

That’s the exception to this feature: because even a device so simple that it relies so heavily on software is subject to the whims of software. You may not be able to get your Chromecast to connect to your Wi-Fi or your phone refuses to recognize the connection. Hardware is the last resort. Unless the physical button breaks or the entire device doesn’t boot at all, it’s a way to restore normality that can’t be compromised by software issues.

And that’s why even on a digitally focused device like a Chromecast, there is still a button to press, just in case.