Chevy Volt Gen 2 BECM Issues

[amsmntparks]

I've got a battery from a 2019 Volt and all the cells are good, but I think the BECM is reporting that the front module has not voltage. The ultimate goal is to be able to plug into the stock BECM and use something like the Simp BMS to control the pack.
I'm using the dbc file from the opendbc github and some of the message ids line up, but a lot of them aren't mapped. I suspect I plugged or unplugged the BECM module into the pack out of sequence and did damage to the BECM (there's lots of warning about this possibility in the manual that I read after the fact), but it could also be that the DBC file I'm using is incomplete or incorrect.
Anyone have any insights?