Lenovo laptop starts, goes off immediately?

Hi there,

Now, when I want to turn on the laptop, it lights up briefly and goes off immediately. Even when connected to the electricity, the process repeats itself all the time.

Reinstalling the battery did not change anything.

The battery can be seen in the picture

Multilayered;

Are all USB ports OK? The center bar must be present, the contacts must not touch.
Disconnect and test connected devices.
Does the computer behave like this even after removing the hard drive?
Has liquid got on / on / into the computer in the past (could be several months ago)?
Test the RAM modules individually.
Test with an expanded WLAN card