Google Pixel 3 is totally crazy - what can I do?

I really hope somebody of you knows I'm in South America (for a year) and can't send the phone…:

1. For some time now, it suddenly suddenly rushes out of the upper speaker (sounds like caged bees) - but mostly only with WhatsApp video calls

2. Yesterday evening I hung my mobile phone to the charger and there it was loaded. When I woke up this morning it was off and did not charge, did not turn on (on the charger it does not load now). I then hung it on a replacement charger from hama and there it did not load, but this sign (see picture) was displayed - about 5 hours. Habs then hung on my laptop and seen on the Internet, that you should press power and quieter key at the same time and that has somehow worked. On the laptop it loads now (nowhere else), but the laptop does not recognize the device and indicates that there's an error.

3. Right now the screen has flickered or on my Bidlschirm horizontal lines have appeared and then flickered

4. The headphones suddenly stop working when I plug them in (USB-3 connector)

Thanks to all who help me with their knowledge!

Your 1st point reminds me of my early youth when I had ECHOS in the lead.

But since you also list other problems vlt you have a virus sounds usually funny and yes the fact is not a cell phone with anti virus program is safe even if the scan shows nothing.

If not tried virus scan

Thanks! I'll try it right away.

Nothing was found - which of course does not have to mean anything…

Anti virus programs bring nothing at all. Do everything only slower otherwise nothing. The screen flickering makes me a bit baffled? 🤔 Hard reset you have already tried.