If it’s Intel I’d propose:
Dump complete firmware, open in FIT, check if Intel® Platform Trust Technology (Intel® PTT) isn’t disabled permanently (two methods, one disables PTT permanently since the setting is fused into PCH first boot)
Re-initialize Intel ME according to:
https://winraid.level1techs.com/t/guide-clean-dumped-intel-engine-cs-me-cs-txe-regions-with-data-initialization/
Empty NVRAM in bios region as far as possible (some machines have their DMI information written there).