Addendum to my first reply.
To the best of my memory this is the way to assign the two zeros to the HDR Power On command using the Harmony One PC software.
Go to the ‘Activities’ tab.
For the ‘Watch Freesat’ activity (or whatever you have called the activity that needs to power on the HDR) click on ‘Customize Buttons’.
Select (if not already) ‘Standard Buttons’ tab.
At the bottom of the ‘Standard Buttons’ tab screen click ‘Add Sequence’.
On the next screen type two zeros in left hand box.
Select PVR (HDR) in middle pull down box.
Select ‘Power On’ in right hand side command pull down box.
Then click ‘DONE’ and follow on screen prompts to copy commands to H1.