Nothing can be done but replacement of the hard drive. At this point, that seems like a no-brainer.
Or something a bit more arcane but nonetheless effective...
You’d think Dell service department could figure that out.
Not accessing the internet is probably not a hard drive issue but a settings issue. Does it boot? Does everything else work? If so then it's 99.99999% probable that it's not a hard drive problem.
If it doesn't boot on the other hand and you are left looking at an expensive brick, it points to the hard drive with the same degree of probablility..