A used iPhone can be the best value in the market. It can also be an expensive paperweight, and the difference is about fifteen minutes of checking.
This is the list we would run through ourselves. Do it with the phone in your hand, before any money changes hands.
Before anything else: the deal-breakers
1. Activation Lock — do this one first
This is the check that matters more than all the others combined.
Ask the seller to open Settings → their name → Sign Out, and enter their Apple Account password in front of you.
If they can do it, good. If they hesitate, claim they will do it later, say they have forgotten the password, or tell you it “does not matter” — walk away.
An iPhone still tied to someone else’s Apple Account cannot be activated by anyone else. Not by you, not by us, not by any shop in India, and not by Apple. There is no bypass, no jailbreak, no service that removes it. The phone is worth its parts and nothing more.
Phones sold well below market price are very often exactly this.
2. The phone must switch on in front of you
Never buy a phone that is “just out of battery”, “needs a new screen so you cannot see it yet”, or is otherwise untestable. A phone you cannot test is a phone whose faults you are buying blind.
3. Check the serial against Apple
In Settings → General → About, note the serial number. Enter it at Apple’s own coverage checker (checkcoverage.apple.com).
It confirms the model is what the seller says, and tells you whether any warranty remains. If the serial does not come up at all, be suspicious.
The check most buyers have never heard of
4. Parts and Service History
Settings → General → About, then scroll right down.
On recent iPhones, a Parts and Service History section appears if components have been replaced. It names the parts and tells you whether iOS recognises them as genuine Apple parts.
If the section is not there at all, that usually means nothing has been replaced.
This is the fastest way to catch a phone that has quietly been repaired. A replaced screen or battery is not automatically a problem — a well-done repair with a quality part is perfectly fine, and we fit them daily. What matters is that you know, so you can price accordingly and ask what else was done at the same time.
A seller who said “never opened, never repaired” while this section says otherwise has told you something important about themselves.
Condition checks
5. Battery Health
Settings → Battery → Battery Health & Charging.
| Maximum Capacity | What it means |
|---|---|
| 90%+ | Healthy |
| 85–90% | Normal for an older phone |
| 80–85% | Ageing — budget for a replacement |
| Below 80% | Replacement due — negotiate |
Also look for an “Important Battery Message” on that screen. It means iOS cannot verify the battery as genuine, which tells you a replacement was fitted with a non-genuine cell.
A worn battery is the least worrying fault on this page — it is a consumable part and a routine replacement. Just make sure the price reflects it. More on when a battery actually needs replacing.
6. The liquid contact indicator
Pop the SIM tray out and shine a torch into the slot. There is a small indicator inside that is white or silver normally, and turns red or pink after contact with liquid.
A tripped indicator does not always mean the phone is damaged — but combined with any other symptom, it changes the picture completely. Liquid damage is progressive: a phone that works today can fail months later as corrosion spreads. See what liquid damage actually does.
7. The frame
Lay the phone face-down on a genuinely flat surface, like a glass table. It should sit flat and not rock.
A bent frame is usually invisible until you try to fit a new screen — and then it will not seat properly. It suggests a heavy drop or, on thinner models, pocket pressure.
Check the edges for gaps between the screen and the body. A lifting screen means either a poor previous repair or a swollen battery, and a swollen battery is a genuine safety issue.
Test everything that can fail
Fifteen minutes, in order. Any of these failing is a repair you inherit.
8. The display
- Open a white image full screen — look for dead pixels, dark patches, discolouration
- Open a black image — look for backlight bleed and bright spots
- Drag an icon slowly across every part of the screen — this finds dead touch zones that casual tapping misses
- Check for green or flickering lines, even faint ones
- Settings → Display → confirm True Tone exists. If it is missing on a model that should have it, the display has been replaced without full calibration
9. Face ID or Touch ID
Actually enrol your own face or fingerprint, there and then. Do not accept “it works, I just have not set it up.”
Face ID that cannot enrol is sometimes repairable and sometimes permanently locked by Apple’s pairing — and you cannot tell which from the outside.
10. Every camera and every mic
- Rear camera: main, ultra-wide and telephoto if present — switch between all of them
- Front camera
- Video on both, with sound
- Flash and torch
- Record a Voice Memo and play it back — that tests a mic and a speaker together
- Make an actual phone call — the earpiece speaker is separate from the loudspeaker and fails separately
A blurry or shaking camera is a common used-phone fault.
11. Charging and buttons
- Plug in a cable and confirm it charges — try wiggling it gently; intermittent charging means a worn port
- Wireless charging, if you can
- Volume up, volume down, power, silent switch or Action button
- Wi-Fi and Bluetooth both connect
12. Will it still get iOS updates?
Settings → General → Software Update.
iOS 27 needs an iPhone 11 or newer, or an iPhone SE from the 2nd generation onward. An older phone still works perfectly well, but it stops receiving security fixes — which matters more if you do banking on it.
That is not a reason to avoid an older model. It is a reason to pay an older model’s price. The full picture: your iPhone will not update any more — is it finished?
Red flags worth walking away from
- Cannot or will not sign out of their Apple Account
- Price far below anything comparable
- Will not meet somewhere public and well-lit
- Rushing you, or discouraging you from testing
- “Screen just needs replacing, everything else is perfect” — you cannot verify anything on a phone you cannot see the screen of
- No original bill and no plausible story about where it came from
- A charging cable of their own that you must use — test with yours as well
Get it checked before you pay
If you are buying anything expensive, it is worth having the phone looked at properly rather than relying on a checklist in a car park.
At iFix Guwahati that is a standard diagnosis: ₹500 for an iPhone, inclusive of all taxes. We check the parts and service history, the battery, the display and touch, all cameras, Face ID, the charging system, the liquid indicators and the frame — and tell you plainly what we find, including anything the seller may not know about.
On a phone costing tens of thousands, that is cheap insurance. And if the answer is “this one is fine”, you get to buy it with confidence.
Buying second-hand and want a second opinion first? Bring the phone to the workshop in Bhangagarh, or message us with the model and what the seller has told you.
Where to repair an iPhone in Guwahati → · Talk to us → · +91 91271 99144
