Wait a minute, "cannot stat nvidia.o, no such file or directory", that's not the actual error. That's just a message that the kernel module failed to finish building. There will be errors before that one that will be a pointer to the actual issue.
Verify the md5sum first, then try, instead of rpmbuild --rebuild whatever, rpmbuild --rebuild whatever >log.txt 2>&1, and post the log.txt file here. That will give a better idea of the problem...