How to Check a Used MacBook for Liquid Damage Before You Buy It

Mumbai's monsoon means thousands of MacBooks suffer some form of liquid exposure every year — many get repaired and quietly resold without disclosure. A MacBook with hidden liquid damage can run perfectly fine for weeks or months before corrosion creeping through the logic board causes a sudden, often unrepairable, failure. Here's exactly how our technicians check before recommending any used purchase.

The One Test Sellers Can't Fake: Liquid Contact Indicators (LCIs)

Apple builds tiny indicator stickers into specific spots inside every Mac — they're white or silver normally, and turn solid red or pink permanently on contact with liquid. They cannot be reset, removed without trace, or faked to look unexposed. The catch: most are inside the chassis, requiring the bottom case to be opened — which is exactly why you should have a technician check before buying, not just inspect the outside yourself.

Visual and Functional Red Flags You CAN Check Yourself

1. 1Smell the keyboard area and ports — a faint sweet, sour, or musty smell often indicates dried liquid residue, even after a 'successful' cleaning
2. 2Check for sticky or unresponsive keys — type every key, including modifier keys (Shift, Control, Option, Command) on both sides
3. 3Look for corrosion or discoloration around ports — greenish or white crusty residue on USB-C/Thunderbolt or charging ports is a major warning sign
4. 4Check the screen for spots, lines, or discoloration near the hinge — liquid often travels down through the hinge into the display assembly
5. 5Test the trackpad thoroughly — clicks should feel uniform across the entire surface; sponginess can indicate a swollen battery, sometimes liquid-related
6. 6Run the Mac for at least 20-30 minutes continuously — liquid-damaged logic boards often show intermittent issues (random restarts, Wi-Fi dropping, trackpad freezing) that only appear after sustained use