[Solved] MacBook Pro 16″ M3 Max encountering MagSafe 3 Blinking Amber LED and Refusing to Charge after update (macOS Sequoia 15.1)

[Julie Hofmann]

Diagnostic Hardware Specs: MacBook Pro 16″ M3 Max | OS Version: macOS Sequoia 15.1 | Archive Source: Apple Support Community #256740581

I am running into a persistent issue on my MacBook Pro 16″ M3 Max running macOS Sequoia 15.1.
Whenever the machine encounters SMC Power Delivery controller handshake fault, the following diagnostic log appears in Console:

AppleSmartBattery: [Power] MagSafe 3 EPR 28V/5A handshake negotiation rejected: resistance anomaly

I verified that hardware connections are intact and tested across different power sources. What is the verified diagnostic procedure to permanently eliminate this symptom?

Mac Studio M2 Ultra (192GB) | Universal Audio Apollo x8p | Logic Pro 11 | Singapore

Logic Pro Audio Producer & Mixing Engineer | "Verified Apple Discussions Archive"

[Donald Bailey]

Apple Recommended / Verified Community Solution

This canonical solution was verified and marked as solved in the Apple Support Community archive.

Completely discharging GaN brick capacitors, cleaning pogo pins with 99% IPA, and triggering PMU cold reset.

Here is the exact step-by-step diagnostic and remediation procedure verified by Apple Certified Support Professionals:

1. Unplug power brick from the wall and disconnect MagSafe cable. Wait 2 full minutes for capacitors to discharge.
2. Clean the 5 gold spring-loaded pins with 99% isopropyl alcohol and a lint-free swab.
3. Plug adapter directly to wall, connect MagSafe to Mac, and power on. The LED will illuminate steady amber.

Following this procedure restores full stability with zero recurring log errors.

MacBook Pro 14″ M3 Pro (36GB) | OWC Envoy Pro FX | iPad Pro 13″ M4 | Calgary, AB

Apple Certified Support Professional (ACSP) | Commercial Photographer & Digitech

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