The easiest and safest way to power your FLORA brooch is with a 3xAAA battery holder.
You can also power your FLORA project with a rechargeable lithium polymer battery which is slimmer and can be taped to the back of the FLORA.
The new bootloader instantly runs your program when battery power is supplies, but earlier versions takes about eight seconds for the FLORA to "boot." You'll see the red onboard LED pulse during this time, then your pixels should light up. Oohh, blinky! If your pixels don't all light up, crimp your wire connections again to ensure they are making good contact.