Welcome to the group. Sorry nobody has responded yet, but this site just came back online and folks are not quite used to checking in here again.
On to your issue... If you chased the issue down to the ECU you can get some help testing from Atlantic EH or possibly one of the guys in MN, assuming you are up that way. Might also want to check in on the Facebook site since a bunch of us hang out over there.
Since replacing the starter relay wheat is is doing? Still cranking when you hook the battery up? Have you eliminated the start button as a potential problem?