Why does my laptop power off after a while?

Question

Do it yourself

Hello.
The ThinkPad 380ed is available. Until recently, it worked perfectly from the network (the battery, of course, died).
Now, after turning on, it works for a couple of minutes and the power in the laptop is completely extinguished - a sharp shutdown + all the indicators are off.
After that, he does not show signs of life for about 10 minutes. Then, when I turn it on, everything is over again.
The power supply stably gives out its 16.55v
I can suggest that it goes into some kind of protection. But which one?
Please tell me in which direction you can start digging?

Answer 1

As one of the possible solutions - try to change the power supply to a known good one. Perhaps the characteristics of the parts that affect the output current have changed