Go to the "Update Firmware" setting, select the "Anycubic_Chiron_V1.3.5.hex" file, and click upload.
However, for those who want a reliable, "set and forget" experience, Version 1.3.5 remains the gold standard for the Anycubic Chiron. To help you get started, let me know: Are you currently ? Do you have stock hardware or have you added mods? Is your PC recognizing the printer via USB? Anycubic Chiron Firmware 1.3.5 Download
Select "Upload Custom Firmware" and browse to your downloaded .hex file. Download XLoader and open the utility. Go to the "Update Firmware" setting, select the