[pippei]

i tried to change boot screen with logo me and accidently flashed a .jpg file instead of a .png now my iphone doesnt boot, it opens to a white screen for about 30 secs and it powers off SOMEBODY HELPP!!

[olliekett]

Have you tried a restore if not this happened to one of my iPhone's restore to the Apple Official FW and take to the Apple Store or your carrier store and they will replace it.

[blkcadi]

Originally Posted by pippei

i tried to change boot screen with logo me and accidently flashed a .jpg file instead of a .png now my iphone doesnt boot, it opens to a white screen for about 30 secs and it powers off SOMEBODY HELPP!!

Try holding both home and power buttons down to force a reboot. If this doesn't work you'll probably and to put in DFU mode and restore.
If the phone is jailbroke DO NOT take it to Apple with out restoring, it will void warranty.