I haven’t tried a cellphone, but I have successfully disassembled and replaced an IPad screen. There are details to be observed, but not that difficult if you are careful, do your homework before plunging in and have the correct tools.
Magic; illusion, as an amateur magician, I've seen this before; the phone is switched after toothpaste is applied, you will notice that the phone is off camera long enough to make a switch. Everyone in the video is involved in this illusion. it is not a very good trick in my opinion.