If you are getting no light at all, try a different power block and a different power cable (except for the Ultra, all Chromecast devices us standard blocks and cables).
Also, do NOT plug you Chromecast into the TV's USB port. Those ports are typically underpowered because they are for attaching a data-stick and not for powering small computers like Chromecasts.
If that doesn't solve the problem, I'm sorry, it sounds like the actual Chromecast has failed. If you've only had it for a couple of months it should still be well under warranty. Here is the link to Google's hardware warranty center:
Thanks for the help here, Byteguy.
Vlad82, I'm sorry to hear that you're having a power issue with your Chromecast with Google TV. We'd like to dig deeper into this — could you fill out this form and let me know once you're done?