Inspecting a Used Android Phone: A Compact Pre-Purchase Routine
· TR Vertriebs GmbH
A brand-agnostic routine for checking a used Android phone before you buy — identity, locks, hardware, battery, software and network.
Android devices come from many manufacturers, and menus, test functions and diagnostic apps sometimes differ considerably. That makes a fixed routine you can apply across brands all the more useful. Allow enough time to inspect a used Android phone, and bring your own SIM card, a charger and ideally headphones. Work through the points in order rather than relying on the visual impression alone.
Start with the identity of the device. Dial *#06#, note the IMEI and compare it with the settings (under About phone) as well as with the engraving and the packaging. Devices with two SIM profiles show two IMEIs — that is normal. Run a status check with the IMEI displayed on the device to rule out blocks or a theft report, and check whether the resolved model matches the device.
Check that the device is really free. Have the seller show you that the phone is at factory settings and does not ask for a previous Google account after setup — this Factory Reset Protection (FRP) would otherwise make the device unusable. The safest approach is to perform the reset and the first setup together and confirm that no unfamiliar account prompt appears.
Test the hardware systematically: check the display for dead pixels, even brightness and, on OLED, for burn-in shadows, and try the touchscreen across the whole surface. Check both cameras, the flash, all buttons, the charging and headphone ports, speakers and microphones, and sensors such as the proximity sensor and compass. Set up fingerprint and face recognition once. Do not rely on manufacturer-specific test codes — they do not work the same way on every brand.
The battery is often the weak point in used devices. Where Android offers a health indicator, use it — on Samsung via the Members app, on other brands sometimes in the battery settings or via a reputable diagnostic app. Also check whether the device charges by cable and, if supported, wirelessly, and whether it heats up unusually while charging. A weak battery is not a deal-breaker, but it is an argument on price.
Check the software integrity. Look for an unmodified operating system without unknown interfaces, for a warning about an unlocked bootloader at startup, and for the date of the last security update. In the Play Store settings under Play Protect, check whether the device is certified. An uncertified device points to manipulated or non-genuine software and should make you wary.
Test connectivity with your own SIM card: a short call, mobile data, then Wi-Fi, Bluetooth and — if you use it — NFC for contactless payment. Check GPS with a maps application. This makes sure the modem and radio modules actually work and that it is not just the display that looks right.
To finish: ask for the original invoice as proof of ownership and warranty, record your findings and let any defects you found feed into the price. Note the IMEI, model and condition and keep the message history. A calm, complete inspection on site protects you far better than a quick glance under time pressure.