Newly installed V3. CH works...HE doesnt!

Just seeing if anyone has come across this issue whilst waiting for any kind of support from Tado.

Just received a V3 wireless stat / HW controller. My setup is a system boiler (Potterton Suprema HE) with a Danfoss FP715si programmer and a Danfoss dial stat.

Gone through setup. Followed wiring guide. The CH works as it should. The HW however will not fire the boiler. The HW test physical button lights up but the boiler doesnt fire.

Ive tried resetting a few times and removed/redone the HW wiring just in case it wasnt sat correctly but still no joy.

Anyone anything similar? Id rather not take it all back to pieces to reinstall the old programmer at this stage