"Discuss the concept of Business Process Reengineering $($BPR$)$ as a transformative approach to organizational change and improvement. Define the fundamental principles and objectives of BPR$,$ highlighting its significance in enhancing operational efficiency, agility, and competitiveness within an organization. Explore the key steps involved in the BPR process and evaluate the role of technology and innovation in facilitating successful BPR implementation. Analyze the potential challenges and risks associated with BPR initiatives and propose effective strategies to mitigate these challenges. Furthermore, examine how BPR aligns with contemporary business trends such as digital transformation and sustainability practices, providing examples or case studies to illustrate the impact of BPR on organizational performance."