Hi All, I had the same problem with my Pro Micro, I uploaded an example with tone (speakers) and it caused my Arduino to not be able to upload any more, it was stuck on “Send V” and the RX Led was constantly on. I managed to get out of this scary situation by shorting the GND and the RST pins twice consecutively just a fragment before I clicked the upload button on the IDE (it came from the Firmware note, saying how to reset and override the bootloader). I must say that it took me some attempts (~ 5-7 times) until I got the right timing but I did. so for those who have the same issue, don’t get desperate and keep trying.
thank you all daniel