radio won't power up on cold mornings

[awelsh]

MY07 TDI sedan, in Canberra. On cold mornings the radio unit will not power up. After 15 to 20 minutes of driving there are several pops through the speakers and the unit powers up.
Is the power control for the radio unit within the unit or a separate module?

[kamold]

Power comes in to the unit from the quadlock harness in the back of the unit. It has a fuse in the unit itself, but there is also another fuse for the radio circuit in the engine bay fusebox.
I've check and clean both of these fuses as a first step.

[awelsh]

I doubt that it is a fuse problem. As stated: after the car warms up - 15 to 20 minutes - the radio unit powers up correctly. This issue started last winter and has recurred this winter; once the weather warms the unit will power up immediately.
There is probably a semiconductor switch for power to the radio unit and it has become temperature sensitive. I don't know where this switch is located.

[kamold]

The radio has constant power. It is sent a wakeup from the canbus gateway, or from the power button.
It will have a soft start circuit on the board.

[awelsh]

The radio has constant power. It is sent a wakeup from the canbus gateway, or from the power button.
It will have a soft start circuit on the board.

Pressing the power button on the radio unit does nothing while the unit won't power up. The unit is totally unresponsive to power button presses on the unit or steering-wheel until the unit eventually comes to life by itself.