cash mkt shorting query

.. what happens if you fail to cover intraday short positions in the cash mkt by close , can someone pls explain what this auction business is all about ? thanks

in simple term, your brokerage house will buy shares for you (that you have short sell) in auction process at bse/nse exchange.. you have to pay price at which your shares are bought . plus penelty of 20%.

Is it possible for an retail investor to participate in Auction through Online Terminal?

No,it is brokers who get it for us.