Thanks for the suggestions.
This GA402R board does not have a coin-cell / CR2032 RTC battery; RTC/EC backup appears to come from the main battery pack, which currently measures 0V at the output (likely BMS protection).
I tested the board on AC only, with the battery disconnected, and also with RAM removed. There was no change — no LEDs, no fan, and no beep codes.
19–20V is present at the DC jack, input MOSFETs, and main B+ rails, but no 3.3V/5V standby (suspected standby inductors read ~0.23V).
Good point about SMBus — I will measure SCL/SDA...
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Last Activity: 02-22-2026, 12:08 AM
Joined: 12-13-2025
Location: Prince George
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I would really appreciate any guidance from experienced members on what to check next or where to focus my diagnosis.
Thank you very much for your time and help.
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ASUS ROG Zephyrus G14 GA402R – 19V present but no 3.3V/5V standby, no power
Hello everyone,
I’m looking for help diagnosing a no-power issue on an ASUS ROG Zephyrus G14 (GA402R / GA402RK series). ❗ Problem
The laptop does not power on at all:- No LEDs
- No fan spin
- No response to power button
The issue started right after a RAM upgrade. The previous owner mentioned there may have been static discharge during reassembly.
🔍 What I have checked so far (with a multimeter)- AC adapter is confirmed working
- 19–20V is present at the DC jack
- Both input MOSFETs have 19–20V on both sides
- Multiple inductors near the eDP connector
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Thanks for your share. wish could be used for my ROG Zephyrus G14（GA402R）Thanks...Leave a comment:
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Thanks for the share. wish I could fix my ROG Zephyrus G14 (GA402R).Leave a comment:
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