When I worked for IBM, they gave me a Lenovo laptop. My impression was that it was a tough, solid piece of hardware. I liked it, to the point where, having need of a new home laptop, years later, I bought one. This was after IBM no longer made them, having sold the brand to a Chinese company. This laptop still had the cute little almost-useless track-pointer set down between the G, H, and B keys; still had the bold THINKPAD logo. I liked it.
This may be news, but laptops tend to get moved around. And since they don't come with handles, they tend to get grabbed by the edge.
It turns out that there is a microswitch inside the Thinkpad -- specifically, the Yoga 14 Thinkpad -- along the front edge, that is intended to warn the PC if it is under abnornal stress - the kind that can cause a head crash on the drive. If the microswitch gets depressed, it will immediately cut power to the spinning hard drive, protecting it. As a side note, it shuts down the PC, too.
My Thinkpad creaks and flexes. And every so often, I squeeze it at just the right spot....