Think of the bootrom as the device’s first breath: a minimal environment, stoic and unforgiving, whose entire job is to listen for a beginning. It speaks in rigid expectations: a particular pulse on UART, a packet or two, a sequence of bytes that say, “I am here. Load me.” When that handshake snags — when the expected rhythm is missing, corrupted, or delayed — the bootrom returns its terse report and refuses to proceed. It is not malevolent; it is precise. Its job is to avoid catastrophe: a corrupted firmware loaded blindly could brick the device, scramble stored keys, or worse, let a malicious actor in. So it waits. It warns. It insists you check the line.