Downgrade my Firmware to 1.6.0 [November 2017] on my Trezor Model One

I would like to downgrade the Firmware on my Trezor Model One. This is for a specific reason related to some missing coins my sister has asked me to help her recover. She claims the coins arrived and were displayed as a “grayed out” entry on her computer screen and then later (and I am assuming after she upgraded her firmware) the coins disappeared completey. They show up on the blockchain under any bitcoin explorer so they are definately there. I am trying to re-instate the trezor back to the condition it was in when it displayed the coins as a greyed out entry. Also, if anyone else has any input as to why the coins would have arrived and been displayed as a greyed out entry I am all ears. My sister has moved all her crypto off the trezor so there is nothing on it now except the alledged coins that are missing. I have put her recovery phrase into an electrum wallet and it did not show me the coins. So I am concerned they are not in an address controlled by her recovery phrase. But at the moment I am simply trying to re-create the situation she describes when the coins were showing up on the Trezor back in 2017. Can anyone help me with the steps I need to perform to install the 1.6.0 firmware? I have downloaded a zip file of it from the trezor github site but I cannot figure out how to get the trezor to load it? Thanks in advance! Kresp.

It’s impossible to dowgrade Trezor One beyond certain steps. In general*, if your version is 1.x, you cannot move to 1.(x-1) or below. That means that (a) if your Trezor is now 1.7 or later, it will not be possible to go to 1.6.0, and (b) all Trezors currently shipping out are on at least version 1.8, so also impossible to downgrade.

You might have better luck telling us more details about the coins that appeared “greyed out”: which application was that? What kind of coin?

On first guess, “greyed out” coins could mean that Suite (or other software) remembers them from a previously connected Trezor session which is now inactive. This would mean that your sister had used a Trezor with a different seed, or a different passphrase.

*) Sometimes the version limits are little different, e.g., between 1.10 and 1.11 the break is at 1.11.1, not 1.11.0.

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