Iphone 6 restart after the logo, please experience in response.

Hello all!
I have an iPhone 6 after flooding, I bought it from a friend at a good price. The phone does not start up after pressing the power button, but when I connect it to the charger or USB, it displays the apple logo and resets after a while, you can still enter iTunes and safe mode when starting via the cable. I have tried many things that I am going to mention right away and therefore I would like to ask for experience in writing advice. Well, iTunes reads ip and when I try to restore or update I finally get an error, usually (4013). I took apart and cleaned the disc in an ipa ultrasonic bath a few times and nothing. I bought a new battery but it's the same. With the display unplugged, too. Do you think there may be a problem with entering the battery tape or rather something of the system stuff? Possibly, I am thinking about hotair and remove the smallest elements from the plate. Write!

Check that the socket min. front camera is not corroded.
Error in 4013 at what point does it appear? Right after unpacking the software?
If so, it may also be something with a nandem, but at the beginning, as I wrote, check the socket, change the batteries and the usb connector.
Flash should preferably be done with only the battery connected and the USB connector tape.

When the phone is flooded, washing it without removing metal screens does not give much. Remove the screens and check what and where is corroded under a microscope. Then wash the discs, replace the damaged elements and the phone should come back to life unless it is damaged nand.

And is it possible to do this by a complete system reset or what? I mean by usb with some program or in the cmd console.

Added after 49 [minutes]:

I'm going to check the camera socket

Added after 55 [seconds]:

And the error appears while waiting for the iPhone's response, as it restarts

For Iphone, the microscope must carefully examine the board 4013, it is a hardware error, often replacing or desoldering the gyro helps, check it.

Iphons run like this without a battery. Logo reset logo reset ... It also does not detect the battery in the circuit and it is best to start looking for a fault with this.