Iphone 8 + Crashing

Hi i just updated my phone i think to the 11.2 version i have an Iphone 8 plus and it keeps crashing what should i do i am pretty upset because i just got my phone in december so this is a frustrating situation my phone restarts over and over again the screen goes completely green or there are green lines. Is this normal? No there is no water Damage and no i did not drop it recently 😟