My guess is that the boot is hitting some untrapped error, possibly harddisk related.
I would suggest:
– removing the power for 10 mins, opening the unit (screws hidden in legs) and disconnecting hard disk. Repower – does it boot now?
I think it is most proberly a disk problem and if so I would remove the drive, connect to a PC and delete all partitions, replace the drive in the 1100S and repower. Hopefully it will format it again without problem.
Make sure that if you are going to open the unit you allow ample time for the capacitors power to drain. Best to disconnect power by removing power supply connection.