It can depend on what is failing as to how you might want to test remote access, but these are some tests that could be helpful:
Test the admin share using this command:
net use \\machine_name\IPC$ /user:domain\ username password
Note: Provide the actual name of the machine you are trying to scan, along with the same credentials that you are attempting to scan with. You can substitute machine_name with domain if you are using local credentials.
To test the remote registry connection:
- Click Start > Run, type regedit, and click OK. The Registry Editor window opens.
- Click File > Connect Network Registry.
To to test the required ports, you can use telnet. Refer to this document:
I'd recommend some online searching to find anything other than this. These are some general tests we use fairly often, but there are many other options that may exist.