>Why does it matter whether it's a hardware or software problem? If it's broken it's broken.
Of course if it's a software problem he shouldn't expect a hardware replacement to fix it, but if he wants a refund he should get it.
It matters because software problems will always exist, there is no bug free software or OS, and the important ones get fixed in upcoming upgrades.
What would he do with his refund if it was a software problem? Switch to some magical unicorn non-issue OS or get another identical machine and OS?
Of course if it's a software problem he shouldn't expect a hardware replacement to fix it, but if he wants a refund he should get it.