Old firmware
Turn off the POS printer. Turn on while holding the paper feed button. Wait for the desired sound signal and release the button. The first signal (switch-on signal) is not taken into account.
New firmware
Turn off the POS printer. Turn on while holding the paper feed button. Wait for the beep and release the button. The first signal (enable signal) is not taken into account.
Further, the main menu with options for operations will be printed. To select a menu item, you need to press the push button corresponding to its number the number of times.