Mint boots from USB, but installation stops with error 5. What should I check?

Passing a capacity test doesn't necessarily rule out every USB problem, and the process used to write the installer can also go wrong. If you can borrow another USB drive, recreate the installer on it and try again. If not, rewriting the current drive with a different imaging tool is a useful next step.

Try another distribution's live installer, or another version of Mint, if that's convenient. If that also fails during installation, it points more toward something common to the machine or installation media than a Mint-specific issue. If it works, focus on how the Mint USB was created and whether that particular image or installer has a problem.

I'd check the laptop's firmware settings before erasing anything. Look for storage-controller options and boot security settings, then compare them with the laptop maker's Linux installation guidance. Don't switch storage modes casually if Windows is still installed, since that can affect whether Windows boots. Keep a recovery route available before changing partitions or firmware settings.

The live desktop working is a helpful clue, but it doesn't prove every part of the installation path is healthy. If you can, check the installer log or error details for the specific file or device operation that fails. That can distinguish a media read problem from a disk write or hardware issue, rather than guessing from the error number alone.

A new laptop can still have a faulty component, but I'd test the simpler possibilities first: recreate the USB, try a different drive if you can, and run the laptop's built-in memory and storage diagnostics. Avoid wiping the internal disk until you have backups and know how you'll restore the system if needed.