The only thing is - and no-one's mentioned this - the firmware upgrades are normally carried out automatically, often in the middle of the night. ÿYou know that something has happened because you switch on and find yourself watching the chameleon!
The auto downloads, that update your sky+hd ,are as stated are normally done overnight.
Your box being on channel 998 is normally an indication that something has changed or you've had a crashed box.
They sofware downloads are targeted at specific models, so if yours has not been updated, its in the line for an update whenever sky get round to it.
They only time you really need to carry out this manual update is if you have a replacement box and want to make sure you have the latest software.
Doing this manually when your box hasn't already updated automatically probably means that the latest software for you box is not in the transport stream yet. So the manual update won't get you the new software update yet either.