Tapping the MODE button twice on the P2 and Photon 2 cause soft power off, like the Electron. I'm not sure why it does that, but it does and goes into HIBERNATE sleep mode and you need to reset the device or remove power to get out of it.
One MODE button tap is the signal strength indicator. Cellular devices do that, but Wi-Fi devices like the Argon did not, but now the P2 and Photon 2 also show RSSI on one MODE button tap like cellular devices.