A common failure point. On some revisions, this is the BAA60B chip.
Check if the power adapter's voltage is reaching the motherboard.
Her multimeter beeped where it shouldn’t. A capacitor that the schematic labeled “N/P” (Not Populated) was present—a tiny, rogue ceramic cap soldered by a factory worker in Shenzhen who’d probably been half-asleep. That cap was creating a feedback loop, singing a high-frequency whine only Marisol’s trained ear could hear.