For the , a "flash file" typically refers to the firmware (KDZ or TOT) used to restore the device via LG Flash Tool or LG UP . A reliable source for stock firmware is essential to avoid bricking the device.
D85530n_00_1217.kdz (Android 6.0 Marshmallow – latest official release for D855) lg d855 flash file
Here is a solid, verified reference for the D855 flash file (stock firmware): For the , a "flash file" typically refers