Taranis "dead" after flashing with C9x (Open Tx)

[bunker]

I just bought a Taranis and after two days I decided to flash it using Companion9x, to the latest version of OpenTx. But after flashing the Taranis appears dead.

What I did:
Follow instructions in the wiki to Flash my Taranis radio
Used SVN opentx-r2834 variant 215.
The progress dialog went all the way to the end.
I closed the dialog and then unplugged the radio.

Symptoms:
Screen on Taranis doesn't display anything when I power on the radio.
I unplugged the battery, waited approximately 15 seconds and then connected it. No change.
No sounds are played on the Taranis.
Taranis is not found on USB in Companion9x anymore.
Charging appears to work when power switch is in off position.
Last time I checked battery level was maybe 30 mins before flashing and it was at 7.9V

Can you please help me troubleshoot? Is there a log-file I can check from the flashing procedure?

[bunker]

Ok, correction, maybe the Taranis was still visible in Windows but Companion would not see it for a while so I could not flash it with the factory firmware.

After pulling out the battery and the card and trying a couple of times to start it and leaving it without power for a while, it was recognized when I connected it to Windows again (Taranis turned off). I could then flash the original firmware. I was still using the same instance of Companion so most likely Companion was not the bad guy in this.

I also managed to flash the latest version. Interestingly enough with the exact same file I tried when the Taranis "died".

After having googled a bit on the topic its worth noting that I do not have USB 3 on the laptop I used.