UniFoxOs is right - they had the incredible presence of mind to immediately start the APU.
But even if there had been any power coming from the heavily damaged engines...the relight procedure (which they followed if I remember correctly) will require to set the engine master switch to off for some time, to permit ventilation of the combustion chamber, after an unsuccessful attempt - at that point there definitely can't be any generator power whatsoever.
Last edited by deptrai; 31st Mar 2013 at 09:32.
Reason: typo