You will need at least one of the codes, either the master code, dealer code, or the installer code, to perform a cell test and jumpstart the communication between Alarm.com and the system. You would also need it to perform a master reset on the panel.
You can try the default codes of 1111, 2222, and 1234 to see if any of them let you access the panel settings.
Qolsys has reported that sometimes performing a power cycle will jumpstart that communication as well. Steps to perform one can be found here.
If you are able to get the system communicating, then you can reset the panel master code in Alarm.com under the Users section. The installer and dealer codes could then be reset using the System Manager section of your Surety.
You’ll also want to ensure that ADT has released the IMEI number. You can do so by entering the IMEI number in our Module Check Tool here. If it is still registered, you will need to reach out to them to have it unregistered.