What could be wrong with the laptop?

Question

Iron

The laptop does not turn on.
More precisely, it turns on for a couple of seconds and turns off again.
It behaves the same with and without a battery.
What are the options? What to try?
The laptop was not flooded with liquids, that's for sure.
I gave it to the service, it has been there for a month, they do nothing.
Tired of waiting, you just want to understand, repair or throw away?

Answer 1

Here, just like with freelancers, look for exactly those who do work of such a level and profile as motherboard repair (has a video on YouTube, can tell a lot), in this case, most likely, a short circuit has formed somewhere - something happened out of order, because of this, the resistance has decreased, but not quite zero, so it turns on, but still the current in the circuit is large and the sensor sees this (in the controller - PMIC - or somewhere else) and protection is triggered.
Or a short circuit is already in that it does not turn on immediately, but after 2 seconds, that is, further down the board, and not the main power circuits.
More specifically, you need to look at the board.
As for the battery, you should still try with it, but without a power supply, although this is me, just in case.

Answer 2

googled the brand and model of the laptop for a similar problem, some kind of clarity may appear

Answer 3

The password is asked to be entered in a pop-up form, and not on a separate page.

And it even says WHAT username and password you need to enter. This is not VP data, but most likely the hoster's initiative and has nothing to do with VP.