Communication restoration between Sonic board and FC

sorry I should have been clearer
this is 4 separate flight parameters
SERIAL1_BAUD
SERIAL2_BAUD
SERIAL3_BAUD
SERIAL4_BAUD

You change those using a flight parameter editor (like Mission Planner or the SkyViper’s WebAP)

The baudrate (lower case) command is what you use when accessing through the debug port (TCP 2017) over serial connection. I thought that was documented in the wiki, but i cannot find it.
Here are some notes I have from a previous post.

Ensure you’re connected to the SV’s Access point, the telnet to 192.168.99.1 on port 2017 using TCP…it should just work.

Also, checkout this post