The NVIDIA TSEC (Tegra Security Co-processor) is a security chip in the Nintendo Switch that is intended to secure the boot process of the gaming console. At this time the function of the chip has been fully compromised in a way that should not be easily patched thanks a dedicated group of hardware hackers and reverse engineers. The writeup below and this post from thishidden on GBATEMP provide some great details on how this was accomplished.
Full writeup here!