DaHai8 wrote:Well, if you can't connect a monitor and keyboard, and SSH is the only way to get to the Pi, then Yes, you Must reformat and reload the SD card.
Your conclusion is correct but the cause is (very likely) something else.
I have observed that not being able to ssh into a newly installed headless gadget mode Pi0 can be caused by removing power too early. A few things happen in the background when the Pi0 is booted for first time.
What I suggest is that you try the following procedure:
1) Prepare the card, update cmdline.txt and config.txt, create ssh file.
2) Plug one side of the USB cable into your computer
3) Plug the other side of the USB cable into the POWER
port of the Pi0
4) Wait for the activity LED to stop blinking (takes a bit of time)
5) Remove cable from the power port and repeat steps 3&4 once more
6) Remove cable from the power port and plug into data port
7) Confirm that ethernet drivers are being loaded on PC
8) Test ssh
Using the power port in step 3 is to assure that the PC does not react on events from the USB port.
IMHO the problem is that removing the power to early can corrupt data on the SD card, like ssh keys that are generated during the boot process.