EVMs can’t be tampered with

Is it possible to vote more than once by pressing the button again and again?
No. As soon as a button is pressed,the vote is recorded and the EVM automatically gets locked. Even if one presses the button again,nothing will happen until the Presiding Officer ‘unlocks’ the EVM through the controlling unit — he does it for the next voter.

When ballot boxes were used,the Presiding Officer would show the empty box to polling agents before the polling resumed. Is there a way now to ensure no ‘hidden votes’ are recorded before the polling?
Yes. Before polling commences the Presiding Officer presses the ‘results’ button to show polling agents that no votes have been recorded on the EVM. Then,a ‘mock poll’ is held wherein each polling agent casts a ‘mock vote’. The Presiding Officer then presses the ‘results’ button to show the recorded ‘mock votes’. After that,the ‘clear’ button is pressed and the polling starts.

Is there a way to ensure that no votes are recorded between the polling and counting day?
After the last vote on the polling day,the Presiding Officer presses the ‘close’ button on the control unit,which will ensure that no more votes are recorded. Also,the balloting unit — which has the buttons — is disconnected from the control unit (controlled by the Presiding Officer) and both are kept separately. The Presiding Officer also hands over a tally of the votes cast to the polling agents. On counting day,this number is compared to the number recorded on the EVM. Any discrepancy is pointed out by counting agents.