How to change Bluetooth music receiver's name and other settings using a serial converter (or otherwise)
After looking at your pictures and checking the USB/Serial converter supplier's site, I would say it looks like you have the serial converter set to 5Volt TTL levels.

I expect you bluetooth module uses 3.3Volt levels.

There's a jumper down by the connector that goes to the breadboard.  From its position, I'd say it is set to 5V.  Disconnect power and move the jumper to 3.3V (to the right) and see if it works.