how to downgrade a ps3 from 3.72 to 3.55 true blue?

hi guys how are you?
iam asking if there a way to downgrade a new ps3(purchased with 3.72v) v3.72 to 3.55 then instal true blue cfw and play with dongle???
and can i play unpatched games on true blue or it has to be true blue patched
and if so where can i get this patches??