: Plug the USB into the projector while it is off, then power it on. Some models require you to hold the power button or navigate to Settings > System Update > USB Update
: The YG300 primarily recognizes FAT32 or exFAT drives; it will typically not recognize NTFS -formatted USB sticks for firmware or media. Photon mono 4 Firmware Update Guide - Anycubic Wiki yg300 firmware