How should I wire a Raspberry Pi to the Fathom S?

Hello,
I have a rapsberry pi, and am wondering how I should connect its serial pins to the fathom board. The 5v and ground pins on the fathom board supply power outward, but the raspberry pi draws too many amps to be powered off these pins. (i am supplying 16v into the fathom.) (i am also using the low light analog camera)
Serial communication only works if these pins are attached however and I am wondering what to do.

You can try GPIO pins 15 and 16, which are the serial UART TX/RX pins.

We definitely haven’t tried it in this configuration and recommend the Fathom-X with the Rasperry Pi. May I ask why you are trying to connect a Pi to the Fathom-S?

I wanted to use the fathom s because it was cheaper than the x. I am building my own rov atm, and I was using the s for serial communication. The reason I was asking how to wire it was bc I somehow fried my fathom s board while using it (Fried my Fathom S ROV side board. Not sure how)
And I still can not figure out how.

edit:
I figured it out! (kind of) i just tested my 12v to 5v converter, and it doesnt work. somehow the converter got fried, so the raspberry pi drew from the fathom instead. now I need to figure out why the converter broke tho.