Section 58(1)(a) in The Representation of the People Act, 1951
(a)any ballot box used at a polling station or at a place fixed for the poll is unlawfully taken out of the custody of the presiding officer or the returning officer, or is accidentally or intentionally destroyed or lost, or is damaged or tampered with, to such an extent, that the result of the poll at that polling station or place cannot be ascertained; or 2(aa) any voting machine develops a mechanical failure during the course of the recording of votes; or