@ajb2k3 said in How do I enter BOOT mode on M5Core2: Wrong boot mode detected (0x0)! The chip needs to be in download mode: @themusicman This means that something else in OSX is access the USBport via a terminal preventing M5Burner from being able to access the port. Please make sure only M5Burner is running and that no other terminal software is running. I tried on my MacBookPro (original issue was on iMac) with no other serial terminal software running, exactly the same issues unfortunately. I have now returned the M5Core2 device back to thePiHut and am awaiting a replacement. Thanks for your support though @ajb2k3 - it is much appreciated.