Please try this steps :
1. Make sure the protective film below the earbud has been removed.
2. Try another charging cable and wall charger to charge the case with the earbuds in it. There will be one steady white light on the case while it's charging and steady white light on each earbud to indicate the earbuds are charging in the case. The light will turn off when they are fully charged.
3. Clean the charging pin with a dry cloth, then put the earbuds into the charging case, and charge the case and earbuds with the charging cable at least for 10 minutes.