The developer incompetence responsible for the Coldcard fiasco

The long and the short of it is that a developer disabled a compiler flag out of desperation in order to get the code to compile, then committed it with the commit message "runs". Specifically, in C: #define MICROPY_HW_ENABLE_RNG (0)

In other words they deliberately disabled hardware RNG.

You can read the full breakdown here: https://insider.btcpp.dev/p/when-randombytes-runs-but-doesnt

The amount of negligence on display here is shocking, and the fact that it went unnoticed for years is just salt in the wound.