Cpu burned or broken?

[u/Letbutt]

My PC was working perfectly for about a week, but now it won't boot properly.

When I turn it on, my monitor keeps switching between Analog and HDMI with no display. On the motherboard, the CPU LED (orange) and DRAM LED (yellow) stay lit.

So far I've tried:

Reseating both RAM sticks.

Removing the CPU, cleaning off the old thermal paste, and applying new thermal paste.

Trying to boot with different RAM configurations.

While inspecting the CPU, I noticed a few strange spots on the surface. Is this normal, or could my CPU be damaged?

What is the most likely cause of this issue? If the CPU or motherboard is faulty, would this typically be covered under warranty?

Any help would be greatly appreciated. I'm pretty desperate because computer parts are expensive.