Issue, pin 3 with a 5L0565 PSU may be caused due a issue with the Pcu, but may also be caused due the motherboard, the extra tuners, or the U1401/U1404 5v regulators.
More about this tuners measurements, see here,
https://jb8a8f8.com/support/index.php?threads/8000hd-tuner-related-measurements.94/

In any case, it's better to measure from the Psu, the Ohm value from this pin, see this picture for more about it.
https://jb8a8f8.com/support/index.php?attachments/dm8000hd-psu-vdc-ohm-measurements-jpg.167/

This pin makes contact or passes several parts as the,
C602
C603
R8
L608
D12

And will eventually end up to the U2
More measurements about this and more, see here,
https://jb8a8f8.com/support/index.php?threads/dm8000hd-5l0565-psu-voltages-measurements.121/
Check in any case the D12 diode if it's caused due the psu side.

There is also a way to activate the psu, without connected to the motherboard by feeding a 3.3v,
More about it, see here,
https://jb8a8f8.com/support/index.php?threads/testing-the-dm8000hd-psu-without-the-motherboard.84/

However be careful with the hot zone side when it's active.