First, why on Earth would you keep making payments on a device that you never received?
Second, I don't know about your device, but mine from a carrier have always had a one year warranty.
At this point, depending on whether the carrier goes by date of purchase or date of receipt, your warranty could be expired.
This means that any service to the device may entirely be your responsibility.
Third- are you still with Boost?
Are you using an old device hat you were trying to replace, and keeping the same service- or were you trying to become a new customer of Boost?
Fourth- like others have said, I am also not a lawyer, but I do know that time is of the essence, and as it has been over a year this is not in your favor.
Neither is the fact that you continued making payments for a device that you never received- all the way up to the point of paying it off early.
I imagine that in a court case this would be one of the first things brought up.
In this day and age, when such a device is shipped, there are many times of tracking its travels.
These are often sent to the customer multiple times via e-mail or other means.
You may find a leg to stand on (albeit a wobbly one, at this point) if you can track down any e-mails showing if and when the device was shipped, and its travels on its way to get to you.
You can also look online to see if others have experienced similar or the same circumstances.
Perhaps they have organized, or you could organize them.
A public 'stinkball' could be rolled out to the proverbial front door of Boost may help you and others in the same boat.
At the very least, misery loves company.
Anyway, also keep in mind that this device is now already a year old. That means that it will most likely be outdated or close to it if/when you get it.
Also in with that is the very real fact that even if it has never been used, the battery is also already a year old. The lifespan of these batteries is something like 2-3 years normally, so even if you do get the device new in the box the battery has already taken a hit just with age.
Unfortunately, these batteries get worn out even if they are not being used, it is just something with the chemistry involved.
Good luck, provide as much info as you can, and keep us posted!