Try connecting a serial cable to the serial interface on the back of the C40 and to your PC, set the baud rate to match what the CODEC is set to, default is 38400. Use a command line tool such as PuTTy or Secure CRT. Hard power-cycle the codec and enter the break sequence during the boot, I don't remember the exact sequence, but it is something like control break or 'b' and 'c'( you should see the instruction on your pc screen).
Then once you break the boot sequence Type "selectsw" minus the quotes and you should see 2 images, Try to select and boot up from the non active one. Once you are booted to the previous version, try to browse, ssh, and ping your C40.
If Successful, attempt the upgrade again, perhaps the image is corrupted. Alternatively you could upgrade to a different version instead of TC 7.3.15 and test to see if it works.
I hope that helps. Let me know if you have any more questions.
Please rate this useful if it helps! Thank you
