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 either doesn't turn on at all, or sometimes it turns on but displays an error screen. When the switch is repeatedly turned on and off, the normal screen appears, and it becomes usable. It's likely the internal power switch is faulty, rather than the power input. This is because when the charger is switched on and off while the machine is on, it sometimes displays an error screen, and sometimes the normal screen, behaving strangely. Once the normal screen appears, the rhythm functions and keys play sounds correctly. If you are familiar with electronics, could you please repair it and use it? Also, the symptoms were the same even when batteries were inserted in the back and the switch was turned on. It can be used once the normal screen appears after repeatedly turning the switch on and off. Therefore, this is a junk item. I would appreciate it if you would purchase it at this price. I am moving soon and would like to sell it quickly. I have discounted it as much as possible! To all those considering a purchase, please consider it! - 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.