My pico ist unable to activate the bootloader to upgrade the firmware 1.93 to 1.99

Hi @jm,

What are the differences between the two switches? Do you can explain that for me?

BTN1 and BTN? Absolutely nothing. They point to the same pin - BTN1 = BTN = C13.

I'm sorry this has all been such a nightmare for you, but it sounds like there's actually a problem with your board and maybe C13 isn't actually connected to the chip itself.

This is the first time I've seen this in ~7000 Pico boards shipped.

digitalRead(BTN) should return 1 when the button is pressed, on any firmware version. And since you checked the voltage on C13 changes I can only assume there is some issue with the STM32 chip.

I'll send you an email in a second and we'll work out how to get you a new board where the button works!