Kastner

If you sure that you have the latest BIOS for the iGPU even that I think rewriting the latest BIOS with the programmer is a good step. If you have an older BIOS then I assume the iGPU will not work. The programmer itself cheap comparing to any hardware and it is pretty easy to use. You already suspecting the motherboard faulty there is nothing to lose to try. If the default setting for iGPU is auto and you remove the GPU then the system should post with iGPU. ( I think) Need someone to confirm the teory since I do not have x170. What is the latest BIOS? Is iGPU setting is AUTO on default?

This is what I found, If you have the latest BIOS you have iGPU setting. I have P870 it does not have iGPU. Also you could try flashing a BIOS If you have CH341A programmer.

Hi, I think x170 does not have iGPU just like P870. It is more likely based on the sympthons that the GPU is faulty. Because the fan speed change and keyboard lit, it seems the EC should work. For the BIOS/EC work the CPU should be working. I am no expert either but I would test the GPU first.