Before you buy
Checking a used laptop before you buy
You get about ten minutes with a laptop you are thinking of buying, usually standing up, usually with the seller watching. This is what to do with them — in the order that finds the expensive faults first, and with a note on what each finding is actually worth off the price.
The run, in order
Confirm the screen is running at its native resolution
Takes five seconds and tells you what panel is really in there. Sellers list the model the range topped out at; a 1920 by 1080 reading on a laptop advertised as 4K ends the conversation early.
Cycle the screen through solid colours
A dead pixel cannot be repaired and cannot be argued away later. On a laptop the screen is the single most expensive part to replace, often a third of what you are paying for the whole machine.
Look at a black screen for light leaking in from the edges
Mild bleed is normal and worth nothing in the negotiation. Heavy bleed usually means the machine has been dropped or the frame is pinched, which tells you more about how it was treated than about the screen.
Check for PWM flicker at a brightness you would actually work at
A laptop screen is one you stare at for hours, often on battery at reduced brightness, which is exactly where PWM dimming appears. It is a property of the panel, cannot be changed, and gives some people headaches within an hour. Invisible in a ten-minute look and impossible to negotiate about afterwards.
Press gently along the top edge of the open lid
Not a browser test, and the most useful thirty seconds of the whole visit. Hinges are the commonest structural failure on a used laptop, they cost a lot to fix, and a failing one feels loose or grinds before it looks like anything.
Lenovo laptops, if this one is a noPaid link: we earn a commission if you buy, at no extra cost to you. A machine that passes the rest of this list is almost always the cheaper outcome, so finish the checklist before you give up on it.
Open the camera and look at the picture
Confirms the camera exists, works, and is the resolution claimed. A camera that will not open at all is sometimes a privacy shutter and sometimes a loose cable running through the hinge — which points back at the previous step.
Talk and watch the level, then play the recording back
Laptop microphones sit near the hinge and share its cable route. This is a second, independent check on the same suspect part, and it takes twenty seconds.
Play the left and right channels separately
A blown or disconnected speaker is cheap to live with and useful to know about. It is also a reliable sign the machine has been opened, since the speaker connectors are the easiest thing to leave unplugged during a reassembly.
Press every key, including the number pad if there is one
On a laptop the keyboard is one assembly: a single dead key and the whole thing is the repair, which on some models means most of the upper case and a price worth knowing before you agree one. Work around methodically and watch the counter rather than trusting a quick run of a sentence. Fn will never light up on any tester — it never leaves the keyboard — so do not read that as a fault.
On any key that felt soft or mushy, check whether it fires twice
The fault that passes a press-every-key check and ruins the machine to type on. A worn contact bounces, one press arrives as two, and it is measured rather than guessed: a gap under about 70 ms is the switch, not your finger. Same repair as a dead key, and the same reason to find it now.
Ask for the charger, and watch it charge
Laptop chargers are model-specific and expensive, and "I will send it on" is how people end up buying one. Plug it in and confirm the machine reports charging rather than merely connected. On USB-C, check it charges from the port you will actually use: a laptop that charges on the left and not the right has a failed port, which is a mainboard repair.
Check the battery health in the system, not the charge level
Windows: run powercfg /batteryreport in a terminal and compare design capacity with full charge capacity. macOS: System Settings, Battery, Battery Health. Under 80% is a battery you will be replacing, and that is a real number to negotiate with.
Plug something into every port
USB ports fail individually and nobody checks them. Bring a stick. A dead port on a machine with three of them is a bargaining chip; a dead one on a machine with two is a problem.
Do it in this order
The order is not arbitrary. It puts the two findings that should end the deal — the screen and the hinges — in the first four minutes, so you are not still negotiating over a speaker when you discover the machine is not worth buying at all.
After those, the list runs by what a fault costs to put right. On a laptop that ordering is unusual, because almost nothing is a component: the screen is an assembly, the keyboard is an assembly, and on many models the keyboard is part of the upper case with the trackpad and the battery. A single dead key is therefore not a small fault, and it is worth finding before the price is agreed rather than after.
Everything before the hinge check runs in this browser, on the machine you are inspecting. Bring nothing but this page.
What each finding is worth
| What you find | What it means for the price |
|---|---|
| Dead pixel | Walk away, or expect the price of a panel off |
| Hinge loose or grinding | Walk away |
| Heavy backlight bleed | Small discount, and a sign of rough handling |
| Battery under 80% health | The price of a battery off |
| One dead USB port | Small discount if there are others |
| Weak or silent speaker | Small discount; check it was not simply left unplugged |
| Camera or microphone dead | Small discount, unless both — then suspect the hinge cable |
The pattern worth knowing
On most laptops the camera, the microphone and the display cable all run through the same hinge. When two of those three are faulty, the fault is usually not in any of them: it is the cable being crushed where the lid folds. That is why the run above checks all three, and why finding two is a much worse sign than finding one.
Before you hand over money
Confirm the machine boots from cold rather than waking from sleep — a machine kept warm and asleep hides a fault that only appears on a cold start. And check the serial number is not blocked or lost, which on a Mac means an activation lock and on a business laptop can mean a management enrolment you cannot remove.
Common questions
What should I refuse outright?
Two things: a screen fault that cannot be repaired, and a hinge that feels wrong. Both are expensive relative to a used laptop, and both get worse. Almost everything else — a tired battery, a dead port, a weak speaker — is a discount rather than a reason to walk away, as long as you find it before you pay.
How long does this actually take?
The browser tests are about five minutes if you go straight through. The hinge, battery and ports add another five. If the seller will not give you ten minutes with the machine, that is information too.
Can I do this without installing anything?
Yes, which is the point. Every test here runs in the browser on the machine you are inspecting, so you need nothing but the address of this page. Nothing you check is uploaded and nothing is left behind.
The seller says the screen is fine and it is just the graphics driver.
It is a claim you can settle in thirty seconds. A driver problem does not survive the solid colour test: a dead pixel stays black on every background and in every application, because there is no signal reaching it at all.
What about the trackpad?
There is no browser test for it yet, so do it by hand and do it deliberately: drag a window slowly into all four corners watching for the pointer stalling, then tap-to-click a dozen times in different places, then two-finger scroll a long page in both directions. Trackpad faults cluster at the edges and in the click mechanism, and both show up in under a minute if you look there rather than in the middle.