Had the same problem with bios write errors and such. But it worked for me when i did the refit process of the clip. And make sure your backup is named correctly. Cuz with the new 3times backup update you have to rename the backup. And they dont mention that either.
It ends with 0,1,2 or something like that but just remove the last number.
Has anyone tried my method i posted in PRO.hacks guide ? (must have working backup)
I restored it from blackscreen and i also got some loop telling me to reinstall system software. Managed to unbrick my slim this way
try and then send me a pm of your progress. And also if you want more info of how i did and what problems i hade with errors and such