Arris surfboard SBG7580 connection issue

Cancelled my account/services on 8/31/2023. My roommate purchased an Arris surfboard SBG7580 as a personal modem and chose to open an account with Xfinity on 9/1/2023. There were some initial issues activating the gateway, but the next day it has resolved and the Internet was working. I went to return the equipment from my account (Xfinity modem & flex) on 9/3 and within moments of returning the equipment my roommate called stating that the Internet was no longer working (on her account, new Arris). 

She followed the steps to get the gateway activated again, but the online reps could not provide any help. The Arris (and related cables) were all working perfectly at 4:00 and by 4:30 we were told that it was an issue with the tech and a technician needs to come out. I have read on several other forums that Xfinity struggles to activate Arris gateways, but then the conversations are taken private and I'm not sure how they are resolved.