No POST after BIOS update for new CPU

Greetings! I?™ve been building PC?™s for decades and have never been this stumped. Hope you can help.

I bought a new B760M-HDV/M.2 D4 MB with the intent on installing an Intel I3 14100F CPU (also new). Knowing that the specs require a BIOS update to handle the chip, I first installed a lesser CPU (Celeron) to do the update. The BIOS update finished successfully - I updated to the most recent version (9.2, I think). I replaced the chip with the I3 and I get nothing but a blank screen. Power to MB, power to keyboard, power to the fans, just no display - no POST.

So, I began trouble shooting. I removed all components except the chip and MB power. I tried 0 memory, then 1 stick (in each slot), then 2. I tried without the GPU, then with. OI tried with different monitors/cables. Of course, I tried resetting the CMOS often (both through the pins and by removing the battery for hours). Nothing would get me to the POST. Eventually, I even re-installed the lesser CPU (the Celeron) and it worked fine - I was able to get into POST. While there I tried updating the BOIS just to the version that would handle the new CPU (I3) - 4.02, I believe. Installed the new I3, no POST, just a blank display.

It?™s not the hardware - the computer boots just fine with the Celeron. I think I?™ve completely narrowed down the problem to something about the BIOS update. I?™ve double checked the files, I?™ve tried a few versions. It just seems to have a problem with the new I3.- which is out of the box new and not damaged (even after 3 installs at this point). For the first time ever, I?™m considering taking it to a shop for a 2nd set of eyes to troubleshoot. I?™m hoping you guys can save me that shame.

Cheers!

Thanks, very useful suggestions. I?™ve done a proper CMOS reset more than a few times through the troubleshooting, So I think I?™ve eliminated any lingering settings.

Your thoughts about the GPU are interesting. I?™ve installed a middle of the road, not too old ASRock (just like the motherboard) Intel ARC A380, which I checked for compatibility beforehand, both with the motherboard and the I3. I don?™t have another GPU to check it, unfortunately.

When I was able to successfully update the BIOS using the Celeron, it was through the onboard iGPU (the A380 was not installed, I was going for minimal components), which I then used after the I3 replacement. After there was no display, I then installed the A380 thinking the update might have forced the need for a GPU, but it still didn?™t display.

I?™d like to hear your suggestions how to isolate the GPU as the problem - should I do an update (using the Celeron) with the GPU installed? If I can eliminate the GPU as the issue, I feel it?™s got to be a defective CPU.