
Discoloration on one of chips (in middle of picture) means that it probably burnt. How or why I am not sure. What that one does I am also not sure. It's name is "copper_26". I'd appreciate if someone more tech-savy with Antminers could tell us what that chip is used for and why might it have burned?
I think Wndsnb is correct, this doesn't seem anything like a chip or even a diode, it's just a 10*3mm piece of copper connected to "copper 27" as shown in the image

Here is the repair manual from Zeusbtc for S17+
https://drive.google.com/uc?id=1TfNMnpEFxEGMHbTr3lmy2-9Ry7XzlgP2&export=download , it has all the pinouts and details about how that hashboard actually works, perhabs someone who understands electronics well enough can help you further (I think NotfuzzyWarm is your guy).
I am also interested to know what happened here, that piece does indeed look burnt/shorted, maybe too much current passed in there?