PS3 99% system update stuck

[Offtherip]

So I was trying to download a cex update, and it got stuck at 99% for the longest so I turned it off and tried going into recovery mode and now it just boots back up to the system update screen, what can I do?

 

[Berion]

If you have read EID Root Key (ERK) on CFW, you can clear cache partition on PC. If you does not have, you need format HDD...

If you don't have ERK but have CFW or your PS3 is a model which can install it, then make sector by sector kind the disk image before formatting (because later you will be able to retrieve data from that image).

 

[Offtherip]

I bought this ps3 like a week ago so I have no idea how to do anything with my hdd on pc! Is there a video or guide ?