If the light on the i3's charging port is white, it is saying it is ready to plug in. If the EVSE on the occasional use level 1 charging assembly is red, it is detecting an internal fault. It's possible the receptacle doesn't have a good ground or the polarity is reversed, or it is defective. Have you tried it in another outlet or just unplugged and replugged it in? If I remember properly...plug the EVSE in first, then plug it into the car's charging port.
2014 i3 BEV, 2021 X5 45e
(The i3 will be sold soon, <17K-miles, interested?)