MacBook Pro 820-02020 Weird behaviour

[Gueric]

Hey mon2, it’s me again. My Mac worked fine a full week, then did the same thing again. Charger would not do anything once plugged in, and battery wouldn’t charge. It’s currently drained,
And only reacts/shows a charging icon when plugged into the top port (slave CD3217, that I replaced 6 months ago). Plugging it in the master port doesn’t do anything.

the trackpad clicks for some reason, even with the charger unplugged.

despite hearing the charging chime and leaving it like that for a while it’s still showing this charging icon. I don’t have access to an ampmeter right now I’m on vacation.

do you have any guess what could be the root cause of this ?
Thank you very much

[mon2]

what could be the root cause of this ?

It is because you are on vacation. Murphy's Law.

Not understanding about the trackpad clicking concern. If there is enough power in the battery, the logic board will allow the haptics on the trackpad to function normally.

Start with the USB-C meter readings for the voltage and current draw. Be very careful about the plugging in and out of the USB-C connectors while being 'hot on the AC power. The USB-C spec is a failure IMHO. The fact that you can easily cross short the many lines on the connector, there is always a risk. While you are charging, the adapter is @ 20v and if you remove while it is 'hot' @ 20v, then 20v is hitting the dainty USB-C lines and causes destruction to the PD controller, etc.

Do check the USB-C connectors on the paddle board on the logic board. Perhaps some clues there.

[Gueric]

Im starting to think aswell that USBC is kind of messed up, especially in MacBook with a power sequence longer than my arm.
what do you think of draining the battery as much as possible to a point where the trackpad wouldn’t even click and the battery icon would stop showing up (by repeatedly pressing keys for example) and then plugging it to power ?
mon2

i ordered an infiray P2 Pro. It’ll help for future repairs, and maybe with my own Mac too.

[mon2]

If you are doubting the battery - just test with another known good unit from Amazon or similar. With Amazon, you can simply return it if not required. Respectively, disconnect the battery to test if the trackpad will click or not without the battery.

I would take voltage measurements of the key power rails to see if something else is taking down the power on sequence. Personally finding the very tiny parts to be nearly impossible to work with on the relatively newer models. While working to service one part, another goes dancing, etc. A true balance of heat; air pressure and a steady hand.