The current consumption fluctuates between 50 and 100mA and is due to the Wi-Fi connection (this is what all modules searching for a Wi-Fi connection or exchanging data over Wi-Fi do, so that's not surprising).

I've re-measured all the connections. I haven't desoldered the module yet.

The humidity was approximately 60%. The module was moved between different rooms after the initial firmware update, but before soldering. An ESD issue could have occurred there.

Thank you for your support.

Greetings,

What is the current draw of the PICO when not soldered to anything (yet doing the same tasks)? Are you sure there are not any issues with the PCB?

I am really in the dark here yet anytime soldering is involved there are concerns.

The problem might be heat related as electronic parts can be sensitive and can only survive a certain level of heat in a given amount of time. As stated ESD can also be an issue especially in dry areas where the relative humidity is less than 30 percent.

Hope you resolve your issues-Brian.

Perhaps it's an ESD-related issue. This is the second time a similar problem has occurred with the Pico, while it hasn't happened with other controllers in a enclosure.

Unfortunately, I can't show a photo due to (future) intellectual property regarding the PCB to which the module is soldered.
Thank you for your input. I'll try to explain the situation in as much detail as possible.
It was soldered manually, but professionally, and then tested for connection and short-circuiting.

When connecting the USB-TTL Downloader, external hardware was disconnected from IO pins G0, G1, and G3 by desoldering solder pads elsewhere on the PCB. EN and 3V3 are not connected.

Do you have any specific questions about the PCB?