Hi,
I have taken a look at your flow, and there are basically 2 things i would like to address:
Connect/disconnect conditions:
The main problem in your flow branches was such as, having both a condition "Power Source Connected" output to 'false' with directly afterwards a condition "Power Source Connected" with output 'false'.
Such setup will never pass further than the second condition because 2 opposite binary states about the same issue can not both be false at the same time.
Efficiency:
When dealing with setting up systems like these, it's common practice to (at least try to) make use of anything as less as possible.
In the case of your flow for example, you would like to setup your sound volume only once at the beginning, because each and every branch of this flow needs this setting anyway.
There is a possibility i could make your flow better, but at least it works now.
Unless it doesn't
-- EDIT --
Also, i don't know why you would want a 100ms delay in your flow before playing the sound (2th branch) but i just left it there for you to alter.