To reboot your Viking or PSAM terminal, please press the yellow clear button and dot/comma button simultaneously to reboot your terminal.
To reboot your OnePa terminal, press the power button for 5 seconds. Now your terminal will do a restart.
To reboot your Castles Npay terminal, press the [menu] or [*] button at the lower left corner until the terminal shuts down or restarts.
Note that you should not disconnect the terminal battery to turn off the terminal as this may damage the hardware.