why does my xperia c sony display no command

[AC Question]

my phone battery died then I charged it but then it started rebooting repeatedly just displaying 'Sony' and as I rebooted the phone again there was a picture of the android character lying down with a red warning image above it and stated below the image was 'No command', the same thing happened twice before(the constant rebooting) but after a while of pressing the on button on the side of it, the phone switched on and worked as normal so what's the problem and is it possible for me to manually fix it ???