Did you recently make any changes to the DNS settings? These can take 24-48 hours to propagate. Also, is the domain hosted by Square Online Store (via Weebly) or is it hosted somewhere else and pointed at your Online Store?
I'll be the first to admit that I'm not the expert on this one - I'd also reach out to Weebly Support, who make and provide technical support for Square Online Store. If you're logged into your Square Online Store account, click here and follow the contact flow to ledge a support ticket.
If you can let me know about the two above questions though I'll do my best to get an answer for you!
I think you're going to be able to get better help from Weebly here - they'll be able to look into your domain and DNS settings and advise accordingly!