JTAG Box's allow you to repair phones which aare dead / not booting. thay allow you to reprogram the boot chip on the phone.
JTAG and eMMC Forensics is becoming commonly used to extract important data direct from the phones memory.
Using JTAG (Joint Test Action Group) extraction techniques will allow you to perform memory dumps of Android and Windows Phone devices.
Recover swipe patterns, PIN codes and passwords from memory dumps of Android devices and in many cases recover live and deleted data from memory dumps too.