I'm not the best person to answer DIY questions, but I figured I'd at least bump your thread and try to point you in the right direction. This thread is probably better off in the
Saber Electronics DIY section than Hilt DIY too.
The simplest thing to do would be to just buy a
Champion PnP kit, PnP LED module, and Momentary switch (lighted or un-lighted) and just gut the current electronics and replace it all. The Champion kit includes soundboard, battery/holder, speaker (all bundled together in heatshrink), recharge port, and pre-wired connectors.
You can easily reuse the current LED by just cutting the wires and adding a micro deans connector. Doing that would save you $40 on a new LED.
Reusing the current battery/holder would make it a bit more complicated, since you'd have to do the whole electronics package DIY. For the $15 cost of battery/holder I personally wouldn't bother. You can always save the current Warrior internals (battery/holder, latching switch, switch cover) to use in an empty hilt later. You'd have to cut the switch wires and re-solder (or use a connector) but that shouldn't be too hard.
If you're looking at more advanced soundboards than what the Champion kit offers, then you'd need to gut everything anyway and use the
Hero Kit, or do a whole DIY install if you prefer a different board or LED setup (such as a 6w/6w LED instead of RGBA).