overheating immediately at 90c

Hello everyone.

Please, I would like to give me some help to the following issue.
It's about the laptop HP 15db1027nv.

With pressing power on button, it burns up. CPU fan starts working from the beginning (with power on), and never stops.
Entering Windows, immediately, Core Temp software shows CPU temp at 90C.

And another that can happen:from Windows it may shutdown without any warning abruptly at 10 minutes (it is for sure because of high temp).

And on a power on session, before start loading Windows, a CPU overheating message from BIOS came up for some seconds only, but I didn't read it all. About 6-7 sentences that had to do with notebook overheating.

I cleaned up cpu fan dust (that dust had been turned into fuzz), and replaced cpu thermal compound. But nothing. With power on, cpu immediately goes to 90C.

What seems to be the problem? Can I do something else to fix the problem?

Thank you for your time.

I managed from 90C to make it work normally on 40C-45C. Too many programs run on Windows startup. Disabled them, and temperature now is on about 40C.

But now I have another not really problem, but I am trying to find the answer to that. Before disabling startup applications, on the pictures below, you will see that I removed from heat sink base the sticker it had on. I was affected by internet reading, and thought that by removing it, it may helped. Here are the three images:

before (original heat sink base from factory):

​https://ibb.co/MZ4nnfG​​​

after my removal:

​https://ibb.co/qChjDVt​​​

Now, when I apply heat sink, without the sticker, the heat sink base, and I am not sure about that, but it is the most possible, must come into touch with the cpu die, as the arrow in the following image:

​https://ibb.co/pxZZ4P9​​​

If it was possible, of course, I would put the sticker back, but, unfortunately, the sticker, from my trial to remove it, it has been ruffled and cut in two pieces. If it is possible, could you please explain me what that sticker was there for? Maybe it is ok not to be there. It was for some protection? For temperature guarding? For isolation?

But, I would like to give you this element, too. Without the sticker, and disabling startup applications, I had switched on the laptop, and, without working on it, just had it on desktop, I left it on for 4 hours. No problem, and for these 4 hours, the temperature oscillated between 30C-45C.

So, can you explain me about the sticker and if danger or not not having it there?

Thank you.