Battery Replacement on Lights with Internal Li-Ion Batteries

My wife's Lezyne Deca 1500XXL stopped taking a charge, at all. Taking it
apart, I saw that the batteries were made in July 2015. Not too good for
it to stop working that soon. These lights don't have user-replaceable
batteries, but by removing two screws I was able to open it, and the
battery pack does have a connector on it so at least they didn't solder
it directly to the printed circuit board.

It's a 2 cell 18650 pack with the batteries in parallel, and a
protection circuit board shared between the two cells. The cells are
allegedly 2800mAH, for a total of 5600mAH. The closest I could find
on-line was a 2x2600mAH parallel pack
https://www.amazon.com/dp/product/B003SH4BV6.

I moved the connector from the old pack to the new pack, plugged it in,
and closed it up. Seems to work fine now.