Hi everyone. I’m stuck trying to downgrade Intel ME on a new Dell Latitude 5531 as part of my effort to restore BIOS and ME to their factory state for testing purposes - the laptop’s TB controller has been acting differently since BIOS was updated.
I managed to downgrade BIOS using a variant of the method described on Dell-PFS-BIOS-Assembler/README.md at master · vuquangtrong/Dell-PFS-BIOS-Assembler · GitHub , but TB controller behavior has still not reverted to its original state after BIOS downgrade, so I would like to also downgrade ME to its original version, a task which has eluded me so far.
I enabled UEFI variable “Me FW Image Re-Flash” which a) produces a brief “(A7) Me FW Downgrade - Request MeSPiEnable Failed” message on reboot, right after the boot logo appears and before the OS begins loading, and b) resets the variable to disabled (0x00) on same.
Flashing BIOS and ME via FPT is not possible, producing errors 167 and 238 respectively.
I have also tried disabling the following without effect:
RTC Memory Lock
BIOS Lock
Force unlock on all GPIO pads
Flash Protection Range Registers (FPRR)
CFG Lock
Also, BIOS Lock and FPRR are disabled by default on this machine.
I’m at the end of my wits on this one, so I was wondering if any experts here might be able to help.
Thank you for taking the time to read this.
Cheers.