Hi there,
and Welcome here…
So it appears to be in a boot loop from a bad OTA slot or flash attempt, Use the Bootloader mode NOW.
(hold BOOT button and press and release the RESET button) check again for the correct com port and try to upload the Blink sketch or a known good demo to put things back.
HTH
GL 
PJ 
You can look at the C3 WiKi to get more info also.