Press the "backspace" key once, then the "#" key once, then the "*" key twice. This puts you into the extended service menu. Now press the ">" key until the display reads "Memory/softswitch," and then press the "Enter/Menu" key to select it. Use these keys again to get to and select "Clear memory," then again to get to and select "Everything." At this point, the printer will prompt you: "Press START to confirm." Do so, and the printer will run a self-test and clear the memory.
This is the proceedure for a factory cold reset. Now, I don't know if you'll be able to do this proceedure since you can't read the language, but you may. You might have to play around with it when it asks you to navigate to "Memory/Softswitch" and "Clear Memory" but it shouldn't be too difficult.
