If there are, I haven't found them. There are one or two decent ones about P2's but that doesn't really help. There is another non-English one, never mind - it is of no help. But your timing is is pretty good! A few pages back a forum member has opened a P3 battery and was nice enough to upload pictures, some of them were even in flames, just to remind you to be careful
And, I just got through taking apart a genuine DJI smart battery I intend to remove the battery cells from and expose the pin-outs in the hopes that I can run something like twin 2s's in series, balanced as a single 4s. More capacity than a standard P3 battery without running three batteries. And, standard, Lipo HV batteries. Well that is the dream anyway

As for your good timing.... Have a look at the pictures I took. My disassembly goes much further than you need to go, but only a disassembly like this will show you where the possible splice possibilities are.
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I have more pictures but have reached the posting limit. I will try to try another posting to keep them together.