A used phone or computer can be a sensible purchase, but its condition is more than the marks on its case. Support availability, account locks and the reset process affect whether you can use it reliably. Check those questions before transferring personal files or signing into the accounts that matter most to you.
Identify the exact model
Ask for the model identifier and storage specification, not just a product family name. Similar-looking devices can have different support periods and capabilities. Check the manufacturer's official support information for that exact model. Do not assume a device receives updates because another member of the same range still does.
The NCSC advises checking whether a second-hand device still receives manufacturer updates and explains that unsupported devices no longer receive those security updates. This can affect the value of an apparent bargain. Compare the remaining useful life with your needs, including the applications you intend to run and the period you expect to keep the device.
Confirm the ownership transfer
Before buying, understand the provider's account-lock or device-management arrangements. A device still associated with someone else's account may not be usable after a reset. A former work or school device may remain under organisational management. Ask the seller to demonstrate the appropriate removal and transfer steps using the manufacturer's current guidance.
If the seller cannot explain a lock or asks you to use a bypass tool, reconsider the transaction. For an online purchase, read the description, return terms and the marketplace's official buyer process. Keep relevant records. A clear return route is more useful than an informal promise that every problem will be easy to fix later.
Reset through the supported procedure
The NCSC recommends erasing a newly acquired second-hand device before use. Follow the manufacturer's instructions for the model and operating system. A reset is not the same as deleting a few visible files. The supported procedure should guide you through removing previous settings and preparing the device for your own setup.
For equipment provided by an organisation, follow that organisation's instructions instead of resetting it independently. It may need management software and a specific configuration. For a personal purchase, do the reset before adding important accounts. If the device repeatedly returns to an unfamiliar managed setup or demands a previous owner's credentials, resolve that issue with the seller.
Test the ordinary work
Check the screen, keyboard or touch input, charging, audio, camera, network connection and other functions you need. Inspect the battery information provided by the system where available. These checks are practical evidence of suitability, not a guarantee of future reliability. Test the functions relevant to your actual use rather than relying only on a successful startup.
Install supported updates through official channels and check that your required applications are available. A student might need video calls and a particular learning platform; a photographer may need support for an editing application and external storage. Confirm those tasks before the return period ends and before reorganising your workflow around the device.
Move accounts in a controlled order
Start with device setup, screen lock and supported security features. Then sign into essential services using known routes. Check additional authentication and recovery arrangements as you transfer them. Keep the old device available until the new one can access the accounts and files you need, especially any authenticator application or device-based sign-in method.
If you are selling your old device, first verify your backup and account access on the replacement. Then follow official steps to sign out, remove account associations and erase the old equipment. Remove removable storage and any physical information you do not intend to transfer. The purchase is complete when the used device is supported for your needs, under your control and ready to handle your ordinary work.
Sources and further reading
This original guide was prepared with AI assistance. Examples are illustrative. The edition date is an assigned date in this 2026 catalogue. See our editorial policy and report a correction.