What does it indicate when a USB-C model pulls 20V but 0 amps/watts?

[SMMRepair]

Have seen two Touchbar boards in the past few weeks, each with the same symptoms: Zero damage to the board, 20v on USB-C input, but 0a and 0w being drawn. Have not seen this prior to these 2 units, but now both are showing this symptom. Have confirmed it's not a charger issue (other boards work just fine with it).

Is there some common issue that causes this symptom? If not, what does this specific power state indicate? The first one had an issue with missing SMC_PM_G2_EN that was being pulled low. Haven't even taken this most recent unit apart yet, but am not looking forward to another perfectly-clean board with no shorts or obvious damage, yet 0a/0w being drawn. I will create a new thread once I have some measurements available, but just wanted to get any information on this upfront. Has anyone had to replace a dead U7800? Suspecting a possible issue there. I've read and heard numerous times that having 20V on USB-C input generally indicates all CD3215's are OK--is this always true?

 

[KC Micro Tronix]

What's the status of your PPBUS ? Voltage? If the machine has shutdown your PPBUS due to short it will still show 20v on the charger but no power consumption.

 

[SMMRepair]

That's the confusing part--no shorts and PPBUS is present, but board is still drawing no A/W. Was hoping someone may have seen this before.

 

[2informaticos]

If SMC_PM_G2_EN is not present, U7800 and also 3V3_S5 are disabled.
In such case, no current drawn from charger.

I think saw few threads on the forum reporting 20V at DCIN and 13V at PPBUS even with a non-working USB-C port.
What I can confirm myself is one 00840 with burnt U3200 (hole on it, damaged USBC_XB_USB_TOP_N pad underneath) indicating 5V on its port and getting 20V on the port corresponding to U3100.

And this is from another 00840 board...
"La placa funciona con un solo puerto USB-C (U3200).
U3200 cambiado, por encontrarlo quemado.
El otro puerto (U3100) tiene corto en la entrada, antes de L3300; causado por un quemazon fuerte en el circuito USB redriver de la otra cara.
Se ha eliminado L3300 (pista cortada).
Al llegar puerto U3200 se quedaba en 5V.
U3100 generaba incluso tensiones en la placa, pero el redriver se calentaba muchisimo, indicando un consumo de aprox 4A."