HPF ERROR not caused by water flow

[cha0s]

So we have a brand new (never installed second hand unit - eg no warranty) pompanette air con. Put it in a week ago. Ran non stop really well.
Turned it off for a couple of hours then when turned back on hpf error came up after a while.
Checked water flow. It was a bit low. (Pump lines too long, muck in water, etc)has been running this way for days so may have caused some damage.
I removed unit and connected it to fresh water on the dock - which has a flow rate of 5 gpm (ie the right flow rate). Unit ran happily for a few minutes making cold air but error came on. Compressor is very hot to touch. Outlet temp of water very similar to ingoing water. Refrigerant tube coming out of the cooling water tube is cool to touch and very hot going in - suggesting the water cooling loop is doing its job.
I don't believe that the refrigerant is low as it ran happily. Is brand new though may have been on the shelf for a year or so. If I bypass the fault codes (ie turn off the error codes on the controller - which is not recommended by the manufacturer ) it does make cold air happily. But I'm not brave enough to do this for a long while was the compressor does feel very hot to touch.

How hot is it meant to get. I'd say it is too hot to touch.

I would stress that even if water flow was low for the week that we ran it it didn't trip out with hpf. We turned it off for a few hours. Then when we turned it back on it tripped out after running for a few minutes.

The compressor starts. It then shuts off.

One other thing that I think we were doing but are no longer doing was restricting the flow of cold air (with a slightly collapsed duct).

Another possibly unrelated issue is the display is telling me weird things like the room temp is going from 7deg f room temp up to 90deg (which is about right) then back to 10 deg. Then it settles down at 90deg for a while. Then the unit hpf's.

We have done a few things wrong. We may have damaged something. What do you think is the most likely damage we have done given the descriptions above.