I reply myself!
finally with:
https://www.mobileread.com/forums/sho...47&postcount=4
on connecting the ereader on computer, simply formatted the partition, on turning on the device all worked fine again.
finally got the prsplus inside my prs-505
thanks you much to people of the forums that answers the questions! good job!
I have done a post in spanish to how to solve some problems I found:
http://blackhold.nusepas.com/2012/06...-sony-prs-505/
maybe could be interesting for those who is difficult understand things in english