Should I tell my boss about this?

I work for a commercial cleaning company. I am cleaning a bank. I was wiping down a desk and bumped a phone. It has a small screen on it and it turned on. I was waiting for it to go to sleep like a computer monitor but its not. I don't want to leave it and somehow get in trouble but I don't want to tell my boss and get in trouble. Should I do anything or just leave it?

Should I tell my boss about this?
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