This rhythm machine is being sold as a junk item. The reason for it being considered junk is likely related to the switches. The on/off switch sometimes turns the power on, sometimes doesn't, and even when it does, it might display an error screen. By repeatedly turning the switch on and off, the normal screen eventually appears, and the machine becomes usable. It's likely the internal power switch, rather than the power jack, that's malfunctioning. This is evident when the charger is switched on and off while the machine is on, causing either an error screen or the normal screen to appear erratically. Once the normal screen appears, the rhythms work, and the keys produce sound properly. If you are familiar with electronics, could you please repair and use it? Also, the symptoms were the same even when using batteries in the back and turning the switch on. It works once the switch is repeatedly turned on and off and the normal screen appears. Therefore, I am selling it as a junk item. The price has been adjusted from the usual Rakuraku 60 to Rakuraku Mercari Takkyubin Collect, and the selling price has been reduced. Thank you for your understanding. - Model Name: MRT-3 - Brand: ZOOM - Output Level Adjustment: Yes - Demo Function: Yes - Rhythm Patterns: Multiple - Power: 4 AA batteries - Real-time Recording Function: Yes - Tempo Adjustment: Yes Thank you for viewing.