Are my IPhone dead?

Heey

First of all, sorry my bad english.

I have unfortunately lost my iphone in a bathtub, so it was totally soaked.
As it happened winked screen and suddenly it went black.

I put it on a radiator for 24 hours but still could not turn it on, so I tried to give it power and suddenly apple logo came up and its actually started!

So it has therefore worked with all the features and now it's dead again? the only one I can is to get Apple logo appears, but I can only when it is powered from the electrical outlet (not usb from the computer) so unfortunately I will not get past apple logo, it goes into the black again everytime after 15-20 seconds.

What could be wrong? it should not be dead when I have had life in it after? and has some advice for what to do?

thanks in advance

The battery is more than likely dead due to the water. Many phone batteries are like this.

USB port on your computer probably does not provide it enough power without the battery, where connecting it direct to an outlet would.

Looks like you may be lucky and a battery replacement "may" solve it for you. It's solved it for me with a couple of phones in the past. (Luckily not my iPhones.)