via http://ps3.gx-mod.com/modules/news/a...p?storyid=2908
Dospiedras, to whom we owe the procedure of downgrade 3.70 to 3.55 , said he had discovered a new revision of METLDR on a PS3 with firmware 3.60 the model is CECH-2504 Datecode and 1B. code retrieved says:


Various methods have been tried downgrading unfortunately without success .... for now. Homepage: http://www.elotrolado.net