Hi,
The protocol has not really been changed by Sierra/BC but the loader tool has obviously been upgraded/changed in the past to cater for various changes external to the protocol.
I have written how to up/downgrade the BC127 a few times on the forum but you can use the DFU wizard which is a available through the CSR support site at the below link, you obviously need to create yourself a login first.
https://www.csrsupport.com/PCSW#s20548
So the procedure to downgrade once you have tool is as follows.
- Power the BC127 and open a serial port to it.
- Send the DFU command to it to get it into the right mode.
- Run the DFU wizard tool and follow the steps through.
Re support, Sierra policy is to support through the commercial channels i.e. you go through your distributor, assuming they are an official one then they should have received some training or at least be able to raise direct tickets with their apps engineer to get it answered. The forum/open community is done on a best effort basis (the best effort is trying to be improved).
Regards
Matt