This DTC is telling you that there is or was an issue with the back up power for the ECM. So the fact that you just replaced the battery, it may be fine and just need to be erased.
So lets start with that. Here is a guide on an xD that should help but we just need to clear the code and see if it comes back:
https://www.youtube.com/watch?v=NTxksOvOTls
If it comes back then follow the testing below on how to find out what the issue is. It could be a battery connection, cable, or ECM. So let us know what questions you have.
Thanks.
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Sunday, February 14th, 2021 AT 9:54 AM