* I have a custom board with an rp2040 on it. I've been using the stock firmware from the designer of the board for a while and its been working fine.
I used https://github.com/NotQuiteApex/picoboot-rs to reflash the stock firmware. This worked fine.
I used picoboot-rs again to flash my own trivial blinking LED rust firmware. The flash succeeded, the LED is blinking, but I can no longer bring the rp2040 into bootsel mode. So I can no longer flash the device.
Has anyone encountered anything like this before?
I've not found any search results about this.

The board does have a TC2030 port on it, so I'm considering buying a TC2030 connector and a debugger to see if flashing a different firmware helps.
But according to https://vanhunteradams.com/Pico/Bootloader/Boot\_sequence.html the state of the flash should have no effect on entering bootsel mode.
So I'm super confused about whats going on. :/