I did the Intel Lab Detection utility thing but it just said "sending online" and suddenly disappeared.
Bit confused as to how that works but anyway..
So if anyone else has a DH87MC, can you get Configuration Mode working?
Or do I have a bad board or conflicting hardware?
Put the jumper back in the normal position. When you then press the power button, hold it for 3-4 seconds (or longer; it takes ~6 seconds on my DZ87KLT-75K). This should get you to the recovery menu (what you called the power button menu). From here, select to enter BIOS Setup (Visual BIOS) and then reset the BIOS configuration.
I have also tried to put my DH87MC into recovery mode, with no success. I've tried everything mentioned in the thread, where applicable, but with no success. I'm trying to clear the TPM. The so called power button menu, also does not appear.
Removing the jumper starts Recovery Mode; that is not what you want.
Keep trying to get to the recovery menu. From the powered off state, press the power button for 3 full seconds. If you hear the system power back down before or as you let go of the button, you held it too long (try again). Keep trying until it works. When it works, you should see a menu that lets you clear the passwords, etc.