Piano Answers

So my friend was going to show off his “supposedly awesome piano skills”.
He played simple tetris & some random bashing. Suddenly, I heard
“PING” noise & my friend I were kind of surprised & found that two piano strings broke.
My friend was freaking out because he was using the school’s piano haha.
Anyways, why did that happen? Was it because maybe he held the sustaining pedal for so long?

Today after winter break a housemate of mine at my college apartment came into my room & started playing on my piano keyboard without asking. I recently brought the keyboard from my house so my girlfriend could practice more. She has been playing it for three weeks without any problems, but when my housemate came in, it shut off, there was a burning smell, & it hasn’t turned on since. I got the keyboard in October of 2003, so it isn’t new, but it was working perfectly until he used it (without asking). I couldn’t see what he was doing with it because I was turned around, so I have no way of knowing what happened.
This housemate is a nice guy usually, & I’ve known him for about a year. He has helped me with computer issues from time-to-time, & I have helped him with various things as well.
My question is, should I ask him to repair/replace my keyboard? He hasn’t offered yet, & I don’t really have the money to go out & buy a new one for $200-$300 like this one cost originally.