POW320D sparked and dead forever

Hi,

I've just received POW320D and happily connected to main power and everything seems to be working fine. I wanted to see what's going on under the hood and connected the RX, TX and GND to my FTDI and two things happened,

1. The load is on always, ignored the button press.

2. GND is removed, device SPARKED and DEAD FOREVER.

https://preview.redd.it/mu68pge19sid1.png?width=1427&format=png&auto=webp&s=5fe73aafd586686769b67aa5d4e362ab83d4c2f0

What's the reason for that? I would like to learn the root-cause.