I have been using Arduino firmware on my Portenta H7 regularly, and I have performed a bootloader update (using the example sketch provided with Arduino IDE) once before. However, after using the same sketch to attempt a bootloader update today, my Portenta will no longer boot. The orange charge LED remains lit (with a slight flicker every ~10 secs), and single- or double-tapping the reset button has no effect.
It will not boot in any mode (DFU, bootloader, normal), and none of my PCs detect that a USB device is even connected. On Linux, there are no messages of any kind from
udevadm monitor or
dfu-util -l when unplugging and replugging the Portenta. On Windows, there are no USB devices detected in Device Manager.
I also regularly use a Segger JLink EDU Mini connected to the 20-pin JTAG header on the Portenta Breakout to debug my Arduino firmware. I thought maybe I could reflash the bootloader using the JLink SWD interface. However, the JLink now also fails to connect to either the Cortex-M7 or Cortex-M4 targets (using Segger tools: JFlash, JLinkGDBServer, and JLinkSTM32).
I'm not sure what else to try. My Portenta H7 is completely unresponsive and unusable now.
Attached are log files showing the output from both JLinkGDBServer and JLinkSTM32.