This issue was faced on Motorola V3C. We have actually faced this issue in our application development, but the same seems to be happening even on the native applications/gallery.

Steps to reproduce:
Fill the native gallery with maximum pictures. Now open native gallery. Now device takes some time to open the gallery. At the same time keep pressing down-key rapidly. Some times gallery is not reached and sometimes gallery is reached and few pages are scrolled down before the device power cycles itself. This same effect is observed even in our application. If any operation takes a moment to complete, and user continuously does the same key presses, we can observe the device power cycle in some time.

Has anybody faced this kind of issue before? Any workaround to avoid this?

Thanks in advance.