Daikin E3 fault on ducted RY125LUY1

[Tupperware]

Hi everyone,
I'm hoping someone might be able to help me out with fault finding an E3 (HP switch) error on a Daikin unit thats 11 years old.

Being right on the new year I can't get anyone for about a week and this week in Brisbane Australian it's 36 degC so it's hurting with no cooling.

The unit runs and seems to start the compressor for say 20 seconds then cycles it off again. The fans don't run at all. The error code comes up after a few minutes. I'm not great at refrigeration, but have checked the following;
- The two PCB fuses are ok
- The HP switch has continuity
- The electromagnet switch for the main power was heavily scorthched (contractor pads) from many years of hard labour, so I cleaned the terminals (no luck fixing the error)
- The PCB green LED is blinking saying no board errors
Everything seems ok, nothing black on the board.

What do I check next?

Thanks for any help.

Cheers
Cameron