It seems Marcus did in fact attempt to format during the boot, if I read his ' formatting shared data partitions' line correct.
Two quick things...Unless I am mistaken, the ' shared partition' is the partition where the logging occurs, and is formatted using the ' exec formatlogdisk' option once in the firmware. It' s odd it is trying to format that, early in the process. But, if you can get any firmware on, attempt to format that using the command above.
Second, if you are going to factory wipe it, there is no need to go down the upgrade path... simply jump straight to the latest 5.0.9.