TS-7670 External Reset
From embeddedTS Manuals
The TS-7670 has a multi-purpose tactile button at a right angle to the PCB. This button can be used as a mechanism to issue a hardware reset to the SBC or as a way to wake up the device from its sleep modes (see Sleep for more information). The stock image for both SD and NAND enable the button to be a reset switch. This functionality can be disabled with:
tshwctl --resetswitchoff
And can be re-enabled with:
tshwctl --resetswitchon