日本采购需求：高压氧舱、高压氧舱、病人监护仪、超声波、AED、呼吸机

I received a pulse oximeter that was labeled "detector1," but I'm having trouble operating it. The instruction manual has text that's too small to read, and even after inserting batteries and switching it on, the device doesn't function. I'm unsure if it's a fault or just a misunderstanding on my part. Additionally, there is no manufacturer information included, and I found your site after searching for the model number on the box. Could you please provide guidance on how to properly use this device? Thanks!