Just upgraded psp to firmware 6.3 How do you downgrade it back to firmware 6.2

I'm sorry, but you can not downgrade it back to firmware 6.2
Any firmware after around version 5.5 cannot be downgraded i think.
It also depends whether you have a psp 2000 or psp 3000
I have a psp 3000 and it was too late for me to downgrade