I've had a nightmare trying to reflash a Libertview/Skybox F5S (not a clone). Tried all sorts of power on things using instructions off page 1. But finally the solution was to use the erom_upgrade_8Mflash tool rather than the Upgrade_PVR800 HD Tool. Worked first time this way using same (new) firmware from their site. Used a Prolific USB to serial with null modem lead as I don't have built in serial.
The link off this site to download it wasn't working but I got it elsewhere, just google: erom_upgrade_8Mflash download and you should find it pretty easy. I can't post links as haven't posted enough on here :-(
Make sure you don't download the iLivid rubbish, use the smaller download button at the bottom NOT the BIG one or you'll end up installing all kinds of cr4p.
Hallelujah. Thought I'd be forking out for a new box, I'd only updated my mates channel list and it had the feint 8/stuck on Load issue.
Hope this helps someone else out the same situation.