Is the marriage of a woman who appointed herself in marriage, without a guardian, valid in the absence of her younger brother and the presence of the ma'dhun (marriage official) and two witnesses?

Most scholars stipulate the guardian (wali) for the validity of the marriage, and a woman cannot marry herself. A marriage contract without a guardian is invalid according to the majority of scholars. If the judge does not validate it, it must be renewed with the woman's guardian. Her guardian is her grandfather if her father has passed away, then her brother, then her nephew (son of her brother), then her paternal uncle, then her paternal uncle's son. If the closest guardian refuses, then the more distant guardian or the judge may marry her off.