Can android(Mi5) phone screen lock be bypassed by Xiaomi service technicians?

[AC Question]

My phone had a power button problem and it failed to turn on, I had given it to the service center for repair who said it will be done shortly but couple of hours later said no spare part will take few days. As the phone wouldnt turn on, I couldnt sanitize it before giving but it had a fingerprint and pin locks. Later in the night, I found my phone to be online in the google security active devices(after service center working hours). It means my phone was connected to the WiFi manually. Can it be bypassed using ADB or any other software that Xiaomi provides? I am suspecting that someone is trying to access the media on my phone at the service center. I am aware that data residing on the phone can be accessed through 3rd party means but if they are able to bypass the lock then they can access all my cloud based information which is really scary!

 

[Rukbat]

There's a file in the phone that can be deleted (even if it's locked) to eliminate the lock.

The service center is supposed to wipe the phone before working on it, but some technicians may not (even if they can be fired for working on a phone with personal data). Print all the screens you can, showing that the phone was online when they had it, then contact the service center manager or owner.