TPM settings missing from BIOS, would re-installing Win10 in Legacy Mode help fix this?

XPS 15 9560, expired warranty

Running a fresh copy of Win10 Home (UEFI) but I keep getting the bootup message "Alert! TPM device is not detected."

Updated BIOS and flashed any other new firmware making sure it's up to date - TMP still not showing up in BIOS under Security.. 

Tried the AC trick, switched off, unplugged for >30 sec then back on but message still there.

Also tried switching off, disconnecting battery, keeping Power button pressed >60 sec, battery connected, AC plugged in and alert still there. 

Would this change if I re-install Windows in Legacy boot mode?? (could TPM show in BIOS after this?)

I refuse to believe that a relatively up-to-date model, running all of the latest updates from Dell would actually require a Motherboard replacement?! for a TPM chip, what's the point of throwing away a good board, CPU, GPU etc just because of an optional chip - can't Dell patch the latest BIOS FW with the same bypass method found in their own BIOS 1.15 version and let us use these machines?

I'd rather pay for a patched bios than throw away a good motherboard..