If you remove the ssd controller and the the short to ground is gone then it's the ssd controller causing the short no? What is the resistance to ground with the ssd controller installed?
Did you thoroughly clean out the flux and ipa from under the SB? Usually when it hangs after installing a known good working SB it was the flux and ipa under the SB (on the solder balls) that's messing with the crystal oscillator causing it to...