If you are trying to emulate an android tv, you must have an appropriate system image for it. Try to look for the corresponding image in your sdk manager. In your case, the system image which you require is Android TV ARM EABI v7a System Image or ANDROID TV Intel x86 Atom System Image. They are available from android 5.0 packages.
Once you have downloaded and installed them, you won't get such a message as No system images installed for this target. And then, you will be able to create an AVD for android tv as you wish.
The following image may help you more. Here, the system images are visible under Android 5.1. You may also find them under Android 5.0.1 as I have mentioned earlier.

Note: Ensure that the Updates/New checkbox is checked in your sdk manager. If it is not checked, you may not get notified about android 5.0 packages if don't have them already in your packages list. Hope you understand what I am saying.
PostScript: I have no idea about your Nexus One issues. Please add some more details to your question, if anything more you have done. It will be helpful for the answerer.