Any DNS Experts Here?

[M A V I C]

Tiangou wrote:
Did he go into the advanced options at GoDaddy and change the nameservers/host-names? If the latter then he gave control over DNS to Squarespace and will need to change the MX records in the Squarespace DNS records panel.

Edit:
Check the MX record propagation for the domain here:
https://dnschecker.org

...If your changes haven't propagated then you've edited the wrong zone file.

And if this is what happened, I would switch the DNS back to GoDaddy. Then update the A record on GoDaddy to point at Squarespace for the website only.