A few days ago, I got a Z270 motherboard, to test a DIMM, as it was not at it's rated 2666 MHz, and it worked fine on the Z270, but a big problem became pretty apparent, literally any change I do to the BIOS, makes the PC reboot, and enter a boot loop state where the PC turns on, ramps up all the fans for about half a second, and turns off, and back on, and so on. Even as simple of a change as trying to enter M-FLASH, that has to reboot the pc in "flash mode", makes the motherboard enter the boot loop. In order to fix the boot loop, I have to reset the bios, and then it works fine, until I try to make any change to the BIOS. Sometimes, but rarely, I am able to do some changes without the motherboard bricking, and in those times, I tried to flash the most recent bios, and it's first available BIOS, and both suffer from the same problem. If anyone has had this problem, and has any possible fix, it would be really appreciated.
What have I tried to do:
-Boot pc without one of it's main components (CPU/RAM) and try to boot the pc normally and see if it wouln't boot loop, FAILED;
-Remove every component that is not needed for the PC to POST (Front IO, GPU, Storage), FAILED;
-Flash multiple BIOS versions, FAILED;
-Trying other CPU (tried with an I5 7400, and a Pentium G4500), FAILED;
-Trying multiple GPUs (GTX 1660 and 660ti), FAILED;
-Trying diferent RAM in different slots, FAILED.

EDIT: Just did the Cofee Lake mod, with sucess, and it still doesn't let me make any BIOS change.
Currently, I am using an i3 8100, with no aparent issues, excluding not being able to change any BIOS setting.