How to Check a Used Phone Screen Before You Buy

The screen is one of the most expensive parts of a phone to replace, and many screen problems are easy to miss in a quick look at the home screen. This checklist takes about ten minutes and works for Android phones and iPhones. Do it before you pay, with the seller there.

Before You Start

• Ask the seller to remove the case and, if possible, the screen protector. Protectors can hide cracks and chips along the edges.
• Make sure the phone is charged and connected to Wi-Fi or mobile data so you can open web pages.
• Turn brightness up to maximum and turn off dark mode, night light and blue light filters for the tests.

1. Look at the Screen While It’s Off

Tilt the phone under a light. Check the glass for cracks, chips and deep scratches, especially at the corners and edges where drops usually hit. Look along the sides for any gap between the screen and the frame. A screen that lifts away from the frame can mean a swollen battery or a poor repair.

2. Run Full-Screen Color Tests

Open our white screen tester in the phone’s browser and go full screen. Check each color slowly from top to bottom:

• White: dead pixels (black dots), yellow or pink patches, uneven brightness and dark corners.
• Black: bright dots (stuck pixels) and, on LCD phones, light leaking from the edges.
• Red, green and blue: faulty subpixels and color tints.
• Gray (type #808080): burn-in shadows on OLED phones. Faint outlines of the keyboard or status bar mean the screen has been used heavily. Our burn-in guide shows what to look for.

3. Test Touch on the Whole Screen

Dead touch zones are common after a drop or a cheap screen replacement, and they’re easy to miss.

1. Hold an app icon and drag it slowly around the whole screen, into every corner. It should follow your finger without jumping or dropping.
2. Open the keyboard and type every letter, number and symbol, especially the keys near the edges.
3. Open a drawing or notes app and draw slow lines across the screen in a grid. Gaps in a line mean a dead spot.
4. Watch for ghost touches: the phone tapping or scrolling on its own.

On many Samsung phones, dialing *#0*# opens a built-in test menu with touch, color and sensor tests. Other brands have their own diagnostic menus, which you can find by searching for your model.

4. Check Brightness and Sensors

• Move the brightness slider from lowest to highest. The screen should change smoothly with no flicker or color shift.
• Turn on auto-brightness and cover the top of the phone with your hand. The screen should dim.
• Make a call and hold the phone to your ear. The screen should turn off (proximity sensor) and turn back on when you move it away.
• On iPhones, test Face ID. On phones with an in-display fingerprint reader, test the fingerprint. Both can stop working after a poor screen replacement.

5. Find Out if the Screen Has Been Replaced

A replaced screen isn’t always bad, but cheap replacements often have worse colors, lower brightness and weaker touch response.

• iPhone: go to Settings › General › About and look for a Parts and Service History section. On supported models it shows whether the display has been replaced and whether it is a genuine Apple part.
• All phones: compare the screen to another phone of the same model if you can. Look for a thicker black border, a duller image, a bluish or yellow tint, or a slightly raised edge.
• Ask the seller directly and ask for the repair receipt.

Red Flags: Walk Away or Negotiate

• Lines, spots or patches on any color test (see lines on a phone screen)
• Areas that don’t respond to touch, or ghost touches
• Strong burn-in on the gray test
• Screen lifting from the frame
• The seller won’t let you remove the protector or test the screen

Quick Answers

Is a scratched screen protector a problem?

Not on its own, but remove it if you can. The protector may be hiding cracks underneath.

Is a little burn-in a reason to walk away?

Light burn-in that only shows on a gray test is common on older OLED phones and is mostly cosmetic. Use it to negotiate the price. Strong burn-in that shows in normal apps is worth avoiding.