I follow the manual method and and It worked. My games, wipeout, Sega Tennis, Lumines ecc.that without hack didn't work played well but after quitting a Lumines game, when I try to start PS vita games I receive this error:
(C2-15411-2) , turn of or disconnect power doesn't resolve the problem. I use again the manual method and this fixed the error. Now It's all OK, and in my 6.20 pstv the whitelist remain active also after a power off or power disconnection not only after a stand by.
Fantastic hack, thanks.
P.s. My PS vita
PS vita fw 3.18 TN-V and TN-X
PSTV fw 3.20 TN-V and TN-X and whitelist updated
PS vita fw 3.51 with rejuvenate hack