Iphone stuck on apple logo it's not responsive

Hi,

I have an iPhone 8 plus which is water damaged when I try to turn it on it stays on the apple logo until it slightly dims (still on the apple logo) until it switches of after a while and it loops. After that it switches of completely

I can't get it into iTunes mode for a software update as it's not responding, you can only turn it on while it's charging and if you take it off the phone switches off after a couple of minutes