斯里兰卡采购需求：库存条码扫描器、Pos 条码扫描器、坚固型条码扫描器、手持式条码扫描器、条码阅读器、USB 条码扫描器

I'm having a recurring issue with my barcode reader purchased from a local seller in Sri Lanka. I've created QR codes with encrypted student data containing special characters, but the reader stops functioning whenever it attempts to scan these codes. The first unit I bought had this problem too, and after contacting the seller, I received a replacement. Unfortunately, the new reader exhibits the same behavior. While the power light and startup sound work as expected, it fails to scan any QR codes after encountering an encrypted one. I urgently need guidance on how to resolve this matter. Your prompt assistance would be greatly appreciated.