印度采购需求：7英寸，COB UART液晶模块

I have encountered an issue with a touchscreen display that I'm using for commercial purposes. The touch functionality has stopped working on all displays, and this is the first time I've faced such a problem. Currently, I have 25 units in stock, and it's crucial for my operations to resolve this as soon as possible. Could you please provide guidance on troubleshooting this touch issue? Any tips or steps to diagnose and fix the problem would be greatly appreciated. Thank you for your support in helping me get these displays back to full functionality.