Many short GRBs show prompt tails lasting up to hundreds of seconds that can be energetically dominant over the initial sub-second spike . In this paper we develop an electromagnetic model of short GRBs that explains the two stages of the energy release , the prompt spike and the prompt tail . The key ingredient of the model is the recent discovery that an isolated black hole can keep its open magnetic flux for times much longer than the collapse time and , thus , can spin-down electromagnetically , driving the relativistic wind . First , the merger is preceded by an electromagnetic precursor wind with total power L _ { p } \approx { ( GM _ { NS } ) ^ { 3 } B _ { NS } ^ { 2 } \over c ^ { 5 } R } \propto ( - t ) ^ { -1 / 4 } , reaching 3 \times 10 ^ { 44 } { erg s } ^ { -1 } for typical neutron star masses of 1.4 M _ { \odot } and magnetic fields B \sim 10 ^ { 12 } G. If a fraction of this power is converted into pulsar-like coherent radio emission , this may produce observable radio burst of few milliseconds ( like the Lorimer burst ) . At the active stage of the merger , two neutron stars produces a black hole surrounded by an accretion torus in which the magnetic field is amplified to \sim 10 ^ { 15 } Gauss . This magnetic field extracts the rotational energy of the black hole and drives an axially-collimated electromagnetic wind that may carry of the order of 10 ^ { 50 } ergs , limited by the accretion time of the torus , a few hundred milliseconds . For observers nearly aligned with the orbital normal this is seen as a classical short GRB . After the accretion of the torus , the isolated black hole keeps the open magnetic flux and drives the equatorially ( not axially ) collimated outflow , which is seen by an observer at intermediate polar angles as a prompt tail . The tail carries more energy than the prompt spike , but its emission is de-boosted for observers along the orbital normal . Observers in the equatorial plane miss the prompt spike and interpret the prompt tail as an energetic long GRB ( the supernova-less long burst GRB060505 and GRB060614 may belong to this category ) . We also demonstrate that episodic accretion onto the black hole of magnetized clouds that carry non-zero magnetic flux can be highly efficient in extracting the spin energy of the black hole , producing the electromagnetic outflows with the power exceeding the average \dot { M } c ^ { 2 } accretion power and total energy exceeding the rest mass energy of the accreted mass . We identify the late time flares with such accretion events .