波兰采购需求：热敏打印机、收据打印机、移动打印机、便携式打印机、标签打印机、条形码打印机

I've been experiencing a persistent issue with one of our printers. The red diode is blinking rapidly, indicating an error. I've already replaced the mainboard, but the problem still remains unresolved. Could you provide any insights or troubleshooting tips for this situation? It would be great to understand if there are any common causes for this type of error or if there are specific parts I should check next. Thanks in advance for your help!