In Bangladesh's booming second-hand electronics hubs—such as Motaleb Plaza, Bashundhara City, and Eastern Plaza—thousands of pre-owned smartphones pass through technician workshops every week. While professional repairs can extend a device's life, dishonest sellers often advertise heavily repaired or water-damaged phones as "100% original, untouched, showroom condition".
Purchasing a phone with low-quality replacement components can lead to ghost touching, washed-out colors, unexpected motherboard failure, and loss of water resistance. Here is how you can inspect any phone like a certified technician before finalizing your purchase.
1. The Liquid Contact Indicator (LCI) Test
Water damage is often invisible from the outside because dried corrosion slowly oxidizes internal copper traces over weeks. Fortunately, manufacturers install chemical moisture stickers inside the phone:
- Where to look: Eject the SIM card tray and illuminate the interior slot using a penlight or phone flashlight. Look inside the bottom edge of the slot opening.
- Normal Condition: The sticker is pure white or silver.
- Water-Damaged Condition: The indicator turns bright pink or deep crimson red. If you spot red, walk away immediately—water damage causes permanent logic board deterioration that cannot be reliably fixed.
2. Replaced Display Detection Checklist
Displays are the single most frequently replaced component on pre-owned phones. Here is how to distinguish an original factory OLED from a cheap third-party copy:
Bezel Asymmetry & Bottom Chin
Copy screens use cheaper display drivers resulting in noticeably thicker black borders around the edges, especially at the bottom chin.
The Water Droplet Test
Place a small drop of clean water on the screen glass. Factory screens have high-grade oleophobic coating that makes water bead into a tight sphere. On cheap copy glass, the water smears and spreads flat.
True Tone & Polarized Glasses
On iPhones, missing True Tone in Display settings almost always indicates an uncalibrated replacement screen. On OLED screens, viewing through polarized sunglasses should remain crystal clear at all angles.
3. Deciphering the iPhone Model Number Prefix
Apple embeds the exact manufacturing origin of every iPhone directly into iOS Settings. Open Settings > General > About and inspect the first letter of the Model Number:
| First Letter | Device Origin & Status | What It Means for Buyers |
|---|---|---|
| M (e.g. MLQ73B/A) | Retail Unit | Purchased brand new from an official Apple store or retailer. |
| F (e.g. FLQ73B/A) | Apple Refurbished | Officially refurbished by Apple with genuine housing and battery. |
| N (e.g. NLQ73B/A) | Replacement Device | Provided by Apple as an official warranty replacement unit. |
| P (e.g. PLQ73B/A) | Personalized Unit | Custom laser-engraved by Apple at time of purchase. |
4. Physical Chassis & Screw Inspection
Examine the bottom pentalobe or Torx screws on either side of the charging port. Factory screws have smooth, unmarred edges and match the exact frame color. Stripped screw heads, silver scratches, or mismatched screw lengths prove the device was opened by a third-party repair technician.