The charging pad will be red when it is plugged in and not charging anything.
Once the earpods are placed on the pad, it should turn blue and green lights should appear on the front of the case of the earpods. The earpods will be fully charged when four green lights appear on the front of them.
If earpods are on the charging pad, but the charging pad does not recognize them, you may need to move the earpods around on the pad until it is recognized.
You can always try a wireless charging phone as well and see if the pad will charge that as a way to test the charging capability.