You have installed RHEL and reboot the PowerEdge server.

The UEFI0073 boot fault combined with explicit notifications regarding a security boot policy failure indicates that the Unified Extensible Firmware Interface (UEFI) Secure Boot mechanism has rejected the operating system bootloader. In the architecture of modern Dell PowerEdge servers, the operating system bootloader image for enterprise Linux environments (such as Red Hat Enterprise Linux) is frequently deployed onto an internal BOSS-N1 (Boot Optimized Storage Solution) controller card. The BOSS-N1 is an optimized hardware-RAID controller holding dual M.2 NVMe solid-state storage drives dedicated entirely to host operating system execution. When the platform security framework verifies the cryptographic signatures of the bootloader file during early initialization phases, any mismatch against the signature keys enrolled within the system firmware results in an immediate execution block. While the underlying cryptographic elements are managed by platform keys, the specific physical component causing the initialization failure loop is the BOSS-N1 storage subsystem hosting the unvalidated OS image. To remedy this behavior, the administrator must either enroll the required Red Hat enterprise certificate authorities or adjust Secure Boot enforcement within System Setup.

Study Guide References: Troubleshooting; Boot Optimized Storage Solution (BOSS-N1); UEFI Secure Boot Architecture.