https://tzheng.us/Tian Zheng — WritingField notes about software, hardware, debugging, and AI-assisted development.2026-07-18T08:14:28ZTian Zhenghttps://tzheng.us/https://tzheng.us/articles/gym-tv-that-kept-turning-itself-on-at-night/The Gym TV That Kept Turning Itself On at Night2026-07-18T08:14:28Z2026-07-18T08:14:28ZHow a black screen, an undervoltage warning, and one ambiguous HDMI-CEC message taught me to debug old hardware with AI.