What did I do wrong?

Hi there,
I've built a few projects but I'm still a beginner at electronics.

I'm trying to build a project where I need separate Voltages.
I have a 20V battery and my idea was to make buy three XL6009 buck/boost converters and wire them in parallel.

I separately tested the modules with the battery and set them up to the required voltage with a multi meter.

The next step was soldering the battery's output to the boards which I did according to the picture.

I finished with the first module and tested it. It gave stable 12 volts so I continued and soldered the second one which should output 8 volts.

When I connected the multi meter and turned on the battery. It was weird since the multimeter only showed few hundreds millivolts then I heard a popping sound and smelled burnt smell.

I quickly turned of the battery and examined the board. My suspicion is the inductor next to the output. It was also really hot.

Can you tell me what did I do wrong? Maybe my terrible soldering job damaged the board?

https://preview.redd.it/bt88vuygbpyf1.png?width=3024&format=png&auto=webp&s=9e8b4e81bfbc0118458666bfaf364ad6e84fa619

Closeup about my terrible soldering job.