Option one.
Connect the STB to the Bose with HDMI. HDMI out of Bose to TV.
If you have a problem with this then try different HDMI cables or a different input on the TV.
Option two
Connect the STB to the TV with HDMI. Connect the optical audio out of the TV to the Bose.
Check the TV and Bose manuals on how to activate the optical output and use the optical input on the Bose.