What to check before buying a used iPhone: a simple field guide

You meet the seller at a cafe counter. The phone is out of its case, screen on, but you can tell something is off. Maybe a hairline crack runs along the corner. Maybe the seller rushes you or avoids a simple question.

• Check activation/lock status and iCloud removal

• Inspect the screen and frame for damage and water signs

• Test buttons, ports, and cameras in person

• Run a battery health check and note max charge capacity

• Confirm included accessories and original IMEI/serial match

Quick scene: start here

You open the Settings screen while the seller watches. You ask them to remove any lock screen passcode and hand it to you unlocked. You tap Settings, About, and the battery page. A few minutes of checking tells you more than a long chat about price.

What to check first: locks, accounts, and carrier

Ask the seller to show the phone unlocked and on the home screen. Then go to Settings and find About. Check the serial number and IMEI there. Ask the seller to confirm the phone is not tied to an Apple ID (they should sign out). If Keep My iPhone (Activation Lock) is on, the phone will need the previous owner’s Apple ID and password to use. Also ask which carrier the phone is on and whether it is locked. A locked phone will need that carrier’s help to switch SIMs.

Physical inspection: what you can’t unsee

Look for screen lift, uneven gaps, bends, and corrosion in the charging port or SIM tray. Shine a light into speaker holes and the charging port to check for lint or greenish residue (a sign of water). Tap the glass across the display to see if it flexes. Turn the phone flat on a table and press down to spot a loose back glass or wiggle. A hairline crack might be fine for function, but a bulging battery or bent frame is a real red flag.

Function checks: press, plug, swipe, snap

Test everything you can in person. Press the home or side buttons. Try the volume and silent/ring switch. Plug in a charger and confirm it charges. Insert a SIM and make a quick call or send a message. Open the camera and switch lenses, then record a short video to test stabilization and audio. Check Wi‑Fi and Bluetooth by pairing a simple device. Open multiple apps to see if the phone slows or shows weird restarts.

Battery and performance: the quick test

Open Battery settings and look at Battery Health. Pay attention to Maximum Capacity; under 80% means shorter daily life and a likely battery replacement soon. Ask about how long a full charge lasts with normal use. Run a CPU-heavy app or game for a minute and look for throttling or overheating. If the phone gets very hot fast, that may point to battery or board problems.

Micro-moment: You hand the phone back after a quick camera test. The seller says it drops calls sometimes. You ask when that started and whether the phone has had repairs. A short answer that avoids details is often a sign to dig deeper.

Repair history and aftermarket parts

Ask if the screen or battery has been replaced. A replaced screen can be fine, but inferior parts can affect touch and color. If repairs were done at a shop, ask for a receipt or a photo of the service record. Third-party repairs that left glue or gaps around the frame are worth a discount. Also note non-original screws, which can mean a board swap.

Price bargaining levers and red flags

If the phone is locked, missing an Apple ID sign-out, has an overheating battery, or a bent frame, start with a significant discount. Minor cosmetic scratches and a replaced screen can be lower-value items but still usable. Red flags that should stop the deal: seller can’t show the phone unlocked, numbers don’t match the listed IMEI/serial, or the phone powers up but reboots or shows strange system messages.

Final checklist before you pay

Carry out these last steps before handing over cash: confirm IMEI in Settings matches the seller’s number, make a call on your SIM, check battery health, confirm the phone is not Activation Locked, and take clear photos of the phone and the seller’s ID if you feel unsure. Keep the receipt and record the seller’s contact in case a problem shows up later.

A clean reset and a quick port check can be the difference between "easy money" and "not worth it."

Today’s takeaway: Treat a used iPhone like an appliance—inspect, test, and document before you pay.