What remedies are available in the first instance?

Constitutional Court Act 1953 (VfGG 1953 last amended BGBl. I Nr. Constitutional CourtAct 1953 of the Republic of Austria  (VfGG 1953 last amended BGBl. I Nr.51/2012 (NR: GP XXIV RV 1618 AB1771 S. 155. BR: 8730 AB 8731 S. 809.)

? 70. (1) The Constitutional Court shall allow achallenge filed if evidence of the alleged unlawfulness of the electionproceeding has been proved and such unlawfulness has affected the result of theelection. In the decision granted to the challenge the Constitutional Courtshall repeal either thecomplete election proceeding or parts of it to be specifically defined.

(2) If the ConstitutionalCourt allows a challenge of an election because a non-eligible person has beendeclared elected, it shall declarethe election of such person null and void. In this case the provisionsof the respective electoral regulation referring to a seat having become vacantshall apply.

(3) If the ConstitutionalCourt allows a challenge of an election because an eligible person has been wrongly declarednon-eligible, the decision shall state whether this causes the electionof other persons to be void, in which case the election of such persons shallbe cancelled. If the contested election has taken place on the basis of partylists registered, the electoral authority in charge shall correct the electionresult it published.

(4) The electoralauthorities which, after the challenge of the election has been accepted, haveto decide on the merits and issue the further rulings, are bound to the actualfacts and the legal view expressed in the decision of the Constitutional Court.[…]

http://www.ris.bka.gv.at/Dokumente/Erv/ERV_1953_85/ERV_1953_85.pdf