I don't know that manually changing information in the files will work, definitely not anything we've tried nor would support.
Once you have the certificate setup the way you want it, I'd recommend the following:
To completely uninstall and reinstall Web Client, I usually use the following (let me know if you have multiple servers installed with Web Client and/or Tenant Services, as they may change the steps.)
1. From Control Panel > Programs > Programs and Features, uninstall Microsoft Dynamics GP Web Components.
2. Browse to C:\Program Files\Microsoft Dynamics\ and verify the Web Components directory is completely gone or empty.
3. Run the 'netsh http show urlacl' script in the Command Prompt: Admin window and verify that you don't see any URL reservations for the following:
-- https://+:443/RuntimeService/
-- https://+:48651/SessionService/
-- https://+:48650/SessionCentralService/
If you see any URL reservations for the port numbers/services mentioned above, use the example script to delete the URL reservation:
netsh http delete urlacl url=https://+:443/RuntimeService/
4. In SQL, delete the existing GPCONFIGURATION database.
5. At this point, you can then launch the reinstall of Web Client for Dynamics GP again.
During the install, we only want to select the certificate on the Runtime Service which is required, we do not want to select it for either the Session Central Service nor the Session Service.
For the Session Central and Session services, we only need to enter the domain account that will be running those two services, which is also what you have/had setup.
For the Runtime Service, we just want to select the certificate that is bound to the IIS site we’re installing onto, and let the host name default in. The exception is if it is a wildcard certificate and would be setup for something like *.domainname.com, as the install won’t allow the ‘*’ so we’d have to enter, most commonly, the server name of the IIS/web server we’re installing on, so the host name of the certificate for Runtime Service would be Servername.domainname.com, for example.
6. Once the reinstall of Web Client is completed successfully including the creation of the GPCONFIGURATION database again, you can launch Web Client via the https://<certificate host name>/GP URL that your certificate is setup to use, and verify whether users now can get logged into Web Client and have the GP application load in the browser, or it hangs again.
If it still hangs, let us know....we may need a support case opened as well.
Thank you