If it "worked before" and does not now, clearly something has changed.
For what it's worth, it seems extremely unlikely that the Dynon circuits have failed if they are giving ANY indication - so it seems more likely that some wiring has failed. Is it even possible for a shunt to fail?
If you want Dynon's help, you should:
a) Provide answers to the configuration questions they posted
b) Re-confirm that all connections are secure, and that each wire has good continuity (e.g. didn't break in the middle inside the shielding).
My bet would be on a bad connection - I have had a couple of incidents of this where a crimp was not done well (originally I used a less expensive crimper, but wised up soon as I discovered inconsistent results).