One or both graphics cards are defective?

I haven't been able to play HD games on my laptop for 4 days.

Either the application is closed immediately, hangs, turns black (together with other applications) or I have to hard reset the laptop.

The few blue screens also point to the graphics cards.

After today's Windows update I also had to do a hard reset because the screen stopped responding.

Built-in graphics cards:

Intel HD Graphics 520 and AMD Radeon (TM) R7 340

My previous attempts: Updates of the drivers (each with an overheat crash on the first attempt) and the BIOS.

Multiple system tests with the pre-installed diagnostic tools and specially installed HP device diagnostic tools - no errors even with extended tests.

Last fall, Windows was relaunched due to frequent crashes and the screen was replaced. The guarantee has expired and only the insurance applies.

Since then, my computer has been very slow, especially on the Internet. Even the font in the browser has become more difficult to read. The problems are increasing. Against other overheating, I bought a coolpad so that I don't burn myself on the laptop.

Now I have installed Afterburner, but I don't know how to use it.

An error and software problem can only be ruled out if the PC is set up properly and then once (without additional software) using stress software such as PassMark BurnIn test that would test CPU, GPU and graphics.
So that's just a "poking around" and a question of belief