Knock a Juniper

How to make a Juniper SRX100H2 reset completely just by rapping the top cover with your knuckles. First I saw it reset as the cat walked over it. Then as I lifted and sat it back down. Took me a while to figure out, but first I tied down the power supply, knocked that one about quite a bit, then discovered this what you see in the clip. Two different units, pretty close in serial number, exhibit the same behaviour. A third unit, with a more remote serial number, does not. I&waiting to hear back from Juniper about this.