I developed a new tool to quickly analyze Samsung Evo 840 SSDs which do not start up properly through JTAG.
It has the following features:
It detects the firmware version from the running code.
It looks whether the SATA PHY is able to see a SATA connection, and whether the firmware was able to establish the connection.
It checks the 8 Flash channels
It analyzes Stack-Traces
It analyzes the Inter-Process-Communication between the ARM cores, and explains their meaning
You can get it at: https://github.com/thesourcerer8/SSDdiag