if you have jailbroken your iphone then do the following: • How to Repair Endless Boot without SSH • Connect iphone with USB and run DiskAid • Copy the following "mobilewatchdog.bundle" from /System/Library/SystemConfiguration/ to your desktop • Delete the above bundle from your iPhone using the "Delete from Device" button • Reboot and wait for springboard. • Quickly install OpenSSH from cydia (you have 10mins before auto restart) • Reboot again after copying back the mobilewatchdog.bundle to the iPhone using DiskAid • Login back using SSH and change the permissions on the following • chmod 755 /System/Library/SystemConfiguration/moilewatchdog.bundle • chmod 755 /System/Library/SystemConfiguration/moilewatchdog.bundle/mobilewatchdog • chmod 644 /System/Library/SystemConfiguration/moilewatchdog.bundle/info.plist • Reboot You need of course to download DiskAid 1st

Hi, I don't thinks it is a hardware issue. To rule out the hardware problem, just restore your iphone in iTunes.