Hey! I apologize for answering this question 1 1/2 years later, but I've made a guide on how to do this: Razer Blackwidow V3 Pro Battery Replacement - iFixit Repair Guide (I haven't found a trustable source to buy batteries for the Razer BlackWidow V3 Pro. If you live on the edge, scroll down to the comments section in the linked guide.)
I really don't know who is going to use this, but here's their battery supplier for who it becomes useful to (Although I don't take responsibility to if this source is reliable or not, it was just a quick Google search :))
I didn't attach a battery in the parts section for a reason. I found one site selling the exact same model number for the Razer BlackWidow V3 Pro battery, but it was from a site I've never seen before and zero reviews on trustpilot. I'll attach it here just in case, but buying it is at your own risk and you may not get what you ordered.
While reassembling, REALLY make sure the display cables and the home button cable won't be folded / bent while closing the digitizer. I'm not exactly sure what I did, but I broke the home button and touch ID since I bent the home button cable to the point that it broke. These ribbon cables are SUPER fragile.
