sochot — Processor / logic board
Critical SoC temperature alarm, tied to a line between power management and the CPU. Either the CPU is heating because of another component on the board, or the line is faulty: a board problem, not a replaceable part.
iPhone
Logic board (PMU↔CPU line / overheating) — check the Wi-Fi and audio areas
Medium confidenceVerified sourceProcessor / logic board
First check
Check with a thermal camera; inspect recently reworked areas, Wi-Fi and audio first.