Originally Posted by FBinNY

It's a complicated question. The original wheel probably failed because the spokes were short and didn't engage the nipple's head. Others have said that, and we're past that issue.

Now, the future.

First, remove the rim tape and see if the end of the spoke is within 1mm or so of the top of the nipple. That's a prerequisite for a proper build.

Then the corrosion which can be tricky, If the rim has eyelets, and you used brass nipples you don't need to do anything. You may want to apply some thin oil product like WD-40 or chain oil between the nipple and rim and spin it out (into the rim). If you do lots of winter riding, pressure wash the wheels forcing water between the nipple and rim to flush out salt (hold a directed spray steady and spin the wheel).

But if you use aluminum nipples and/or don't have eyelets in the rims, the hole will be super vulnerable to salt. Salt will wick into the gap between rim and nipple and start attacking the aluminum. Prevent this by applying a heavy oil, or grease thinned with solvent between the nipple and rim to keep water and salt out, and pressure with water and detergent every Spring.