could you please specify "a powerfull laser"?
i very much dought that you can damage anything on your phone with standard class 1 and 2 lasers, which are more or less eyesafe. you would have to tightly focus a class 2 laser and even then the power would still too be low. a class 3 laserwould do the trick but i wonder what your friend is doing with a class 3 laser, its not that you would get them for a few hundred bucks at wallmart. anyways, i ld say anything above 10TW is a powerfull laser...

just a small comment, a green laser is not more powerfull than a red one. the human eye is very sensitive to green light, thats why you think it is very strong, but you can only tell by reading its specs.