So I was messing around with my new RP2040 connect, flashed micropython, and then was no longer able to double tap the reset button to enter bootloader mode, nor was I able to flash any Arduino sketch (holding down the button also does not work like the pico in any case). How do you fix this? Pretty easy, you just put a jumper on (or short them using something else) the REC and GND ports right next to each other (not RST/GND), plug it in, and it will be in bootloader mode where you can then nuke the flash and re-upload an Arduino sketch to it!
There may also be a way to enter bootloader mode through micropython itself, but I was not able to get any of the commands to work.
And now I see that this was already mentioned here heh, I'll just leave it in case its helpful to anyone who is googling.