A Question about battery rebuild for 600E

[CreeperLoop]

Hey guys, : )

I'm new to here and recently bought a IBM 600E with a dead battery. Did some researches and it seemed like the chip inside the battery won't need to be reprogrammed (like T4x Series) after changing the cells. Therefore I'd like to give it a shot, using fresh Li-polymer cells with similar size to the original 18650 sets.

The question is that I found some extra soldering points than positive and negative poles on the circuit, and the layout of those PCBs are kind of hard to find. Could anyone who has experience on rebuilding these batteries share the techniques on how to solder the wires and the ways to check the voltages of those pins?

Many thanks!
Jim