Posting in case my experience helps anyone else.
I managed to brick my box by not fully removing my previous channel list of my F5S box before adding a new channel list. This caused my box to display the message 'aSH'. I couldn't do anything. I then managed to stumble across this forum via Google and followed the original post in this thread - after buying the RS232 Null Modem Cable I them proceded to follow the instructions using the files which are made available in the original post.
On running the Erom update I kept getting the "Wrong File error" - I immediately presumed I had a cloned box and then went on to download all the various clone firmware which are mentioned throughout the entire thread. Still no luck. I then located another version of the Erom Update Software and thought maybe there was an issue with the original software. Ran the new software and followed the instructions, progress was made, I now managed to get my box to stop displaying 'aSH' and was now at least trying to load. Going from L001 but then stopping at L093, before displaying the E001 Error.
It turns out I was still using the wrong firmware. Luckily i complained to the supplier of my box about it being 'faulty' and they sent me a new one. So the first thing I did when the new one arrived was to backup the firmware and channel list to USB. I then used this copy of the firmware on the original 'faulty' box and hey presto the box is now working again! Excellent.
I don't know why all the different types of firmware I tried didn't work, but this one sure did.
I've attached the Erom Client which worked for me along with the backup of the firmware in the hope it helps someone else out, I know how frustrating this can be!
The information on my SkyBox F5S is as follows:
Main Chip: ALI3601 HD
OEM ID: 0001
Peripheral unit: RS232, CA Slot> NET, GPRS
Display Mode: FULL HD
Memory Size: DDR2, 128M
Software Ver: M6_HD__27_03_2013_0794