Mk167 HELP

I just finished soldering my MK 167 tealight candle kit, and when I put the battery in it wouldn’t turn on. This is my first project, can anyone offer some advice?

This kit contains 6 electronic parts, so it cannot be difficult to troubleshoot it.

Check all solderings
Check direction of the led
Check direction of the µ-controller
Make sure you did not swap the resistors
Check the soldering of the battery connector
Make sure battery is correctly inserted
Check battery with multimeter.