1st and foremost seeing his post saying that recommended kernel didn't work I am assuming he owns an arc device and just got lost in this thread.
2nd he probably downloaded the 1st kernel and got corrupt while downloading and tried arcknight and managed to boot up till bootscreen and still failed.
3rd he tried flashing an arc kernel on an Xperia Pro device has 70% chance of permanently bricking his device. Each kernel has different boards and uses different instructionsets. Flashing a different kernel on your device has a very high possibility of burning out the board of your device. He's just lucky Arc and Pro uses the same board(mogami). If he tried flashing a Xperia Play kernel (using a zeus board) I don't know what would have happened