> Or a JTAG interface that the chip has in silicon and recovery is always possible from bare-metal. Dunno if that’s technically in the MCU’s bootloader or if th

> Or a JTAG interface that the chip has in silicon and recovery is always possible from bare-metal. Dunno if that’s technically in the MCU’s bootloader or if the boot loader comes after. If the vendor's actually trying to lock down the platform they'll usually burn the JTAG fuses as well. It's hit or miss though, I've definitely come across heavily locked down devices that still have JTAG/SWD enabled. Edit: To your question, JTAG is usually physical silicon, not part of the bootloader.