That’s weird – sticks DO plug straight into the TV. Expresses have an HDMI cable from the Roku to the TV. Do you have a 4-digit model number? Does it show the model number in your Roku account?
When I said code, I was talking about an IR code set that you need to program into a universal remote that tells it what kind of device it is controlling. These are typically listed in a document that comes with the remote control. (If we are talking about a “Universal” remote that controls many devices.)
By the way, I have managed to find people’s old SSID/passphrases stored on the phones or laptops. For example, on an Android phone the path is roughly: Settings -> Network & Internet -> Internet -> Saved networks -> [select your old network] -> Share. This brings up a screen with a big QR code with the Wi-Fi password displayed under it. (In tiny text that you might miss if you aren’t looking for it.)
