<human>: Can you succinctly summarize the text in 1-3 sentences?

Question: What to do in following scenario.
So for the info: I found out about it because it wasn't in the place where I left it when it charged and the backpanel wasn't fully clicked on and the phone had been restarted (was at the insert sim pin-code screen but when I left it for charging it was on the login code that's for the phone).
So here's a guess of mine: She tried to access the phone, when it didn't work since my phone need a code she put in her sim-card and used her pin-code though she still couldn't access the phone since she needs the phone code. She doesn't know how to correctly put on the backpanel on a S3 and doesn't snap a part of it. I know it's her since no one but she and me has been home today, I haven't found any traces that she has gotten into the phone anyhow but I still doesn't feel very happy about she trying to use my phone without asking.
<bot>: My bitchy stepmother tried using my phone without asking, even changed to her sim-card. I'm not happy with people using my stuff without asking so I wonder what should I do now?