Security

My reseller refurb iPhone 6s turned out to have a 3rd party screen when I took it to the Apple Store to replace the battery. Unfortunately, Apple broke the "flex" of the Receiver at the top of the screen so the front (selfie) camera doesn't work and nor does the iPhone Sound except on Speaker (which means the room can hear what my interlocutor is saying). I've had to take it back to the Reseller for repair (£69). I had switched the iPhone 6s off but the Reseller technician asked for my Passcode which I gave him. I realised as I walked away maybe I should not have so visited Starbucks to have a coffee and disconnect my iPhone from iCloud. Is this enough to preserve my data? Can the techie who I trust but maybe shouldn't access Keychain or any other sensitive data. I have Touch ID enabled and I think Face ID on one site.