As you are unable to rdp the machine and unable to re-install the agent, I suggest the following method
- Create a new VM in the same virtual network and with a local IP in the similar range of the VM
- Access the VM from the new VM through RDP using the local IP address
- Check the files under the following folders and see the exact issue for this error and troubleshoot accordingly
C:\WindowsAzure\Logs\WaAppAgent.log
C:\WindowsAzure\Logs\TransparentInstaller.log - If that doesn't help, I suggest to re-install the package as explained the following article:
windows-azure-guest-agent - If the rdp connectivity is not working, you can try accessing the folders within the VM by accessing the files like \<computer-name or IP>\C$ and check the above logs indicated in the step 3
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