Does the PSP shut off after a while, if you don't touch anything?
When I turn on the PSP, when there is a battery inside, the lamp turns green, but there is no any picture or sound.
Does anyone know what poblem could this be?
If it does, how long does the green light stay on for?
If it stays on indefinately, or shuts off after a while (As in around 3-10s)... your firmware is probably corrupted.
If it shuts off very quickly, then you might have a blown fuse inside the PSP.
BTW: Are you certain that it doesn't emit any sound at all? Sometimes, it's just your LCD's backlight that isn't working for some reason, and graphics can still be seen if you shine a really bright light into the screen.
Unmodified SCPH-77006 with SM 3.6
SCPH-39006 with M-chip modchip, SCPH-10281 NA and refurb Seagate 80GB HDD
SCPH-10000 v1.00 with SCPH-10190 PCMCIA NA and SCPH-20400 HDD unit