Since Rocket Lake release I have seen quite a few people post about the board acting like it is dead or one of the bios will not flash on a dual bios MB like Apex.
I ran into the same issue with z490 Unify and 11900k where the MB would not do anything.
Someone on a German site just posted about this with z590 Hero and 11900k and they could not get the MB to post or flash the bios via flashback. I suggest removing everything(so just MB and PSU) and then try flashback and it worked for him so posting it here. Try it as a last chance if nothing else works.
Disconnect everything, Sata, NVME, RAM, CPU etc. and then try flashbackhttps://www.youtube.com/watch?v=28okjfzHMMA