Thank you Branch Delay, NiLuJe, knc1, eschwartz and all the mobileread community.
I jailbreaked my PW3 S/N G090 G105 Spanish language friday night with the Kindlefere link and copying both the jb file and NiLuJe hotfix beforehand, everything seems to be working fine and I'm now on fw 5.7.2, however I did run into an issue when jailbreaking...
When I got the message that the jailbreak was successful I forgot to turn airplane mode ON, then I tried to apply the hotfix but the update message was grey out. I connected the Kindle to my laptop and copied the file again and after removing the Kindle for the laptop I noticed most of the screen was blank except for the top menu bar. After a while I tried to turn off the screen but it just went all white and after several seconds all black. Then it rebooted on it's own, I applied the hotfix and that was it.
I was wondering what could have caused it (probably something I did wrong) and if I should be worried about having problems with my device later on because of this.