Personal data at risk during iPhone 5s battery replacement?

My iPhone 5s battery was old and not performing well, so I decided to replace it.

I took it into a store that serviced iPhones and Samsungs.

The battery was completely dead when I handed it over to the technician, I had a passcode on the device and did not erase any of my data prior to handing it over. In ten minutes, the battery was replaced. The technician then connected my iPhone to his computer via USB cable and said there was only one more step to carry out, which was to double check that the iPhone was original - or something along those lines - I can't recall exactly. He asked that I input my passcode then to click 'allow trusted device' on my iPhone so he could access it via his computer to make the check. My iPhone would have been connected via USB to his computer for no longer than 30 seconds while he 'checked' something in the settings. I couldn't see exactly what he was doing, but I let him do his thing until he said 'everything was fine' and I unplugged the USB. During this time, it didn't appear he was accessing or copying personal data - but perhaps I wouldn't necessarily know. I have since ensured reset all 'trusted devices' in iCloud settings.

My questions is, during this period (the actual replacement of the battery and the 30 seconds it was connected to his computer) are:

1. Is it possible for my personal data (photos, data, personal info) to have been at risk during the actual battery replacement itself when the inside of my iPhone was opened up (no passcode had been given to the technician)?

2. Is it possible for my personal data (photos, data, personal info) to have been at risk if I didn't see the technician actively 'downloading' my personal data or photos? I realize it would be possible if I had left the iPhone in the technician's care much longer and he actively went about this - but other than that, is there anyway other way it could have been at risk that I may not know about?

3. Finally, what was the check the technician wanted to make by connecting to my iPhone - and was it necessary?

Thanks in Advance!

SWP