I have been uploading different samples to one of the ESP-WROOM-32 devkits we purchased a few weeks ago and up until today everything worked fine. Today, however, the devkit appears unresponsive: connecting it to the PC does not create /dev/ttyUSB0 as it always did. The red LED does light up and the ESP32 module heats up (as expected), but the PC does not recognize the device. After a while, I notice that the LED flickers somewhat, but it does not change the problem. I tried connecting a different devKit and that works as expected, so the problem is not the PC, but rather the actual devkit device.
further troubleshooting using
udevadm monitor
confirms that the second unit (the working one) generates "add" and "remove" events, but the first one (bricked?) does not. Pressing the EN an/or BOOT buttons does not change anything. lsusb does not list the device either.
So is there a way to un-brick this? Or further troubleshoot this without probes or scopes?
thanks for your help!
setup: Linux aisen 4.9.8-1-ARCH #1 SMP PREEMPT Mon Feb 6 12:59:40 CET 2017 x86_64 GNU/Linux