Welcome to Android Central! It's unlikely that the Play-Doh is the reason why the phone won't turn on. Assuming a child got a hold of your phone (hence the Play-Doh), he or she most likely dropped it as well or otherwise caused damage (like maybe water damage). You'll probably have to bring it to a repair shop to diagnose the problem. In the future, if you're concerned about spending money on your personal device, then take good care of it -- don't let children handle it.