This could be so many things the way you describe just stopping then 'no clicks' you would really need to test things, if possible with a scanner, it could be ECU (not impossible but unlikely), fuses, relays etc etc. But the main culprit you should test first is the battery, because petrol engines (most are in USA) do not run or function without electric, now before you start screaming hold on a minute. Even replacing the alternator will not charge a bad battery, that should be the first check, we have many techs on these forums who I'm sure would agree. If the shop you've put it in haven't done anything in a year then you are being ripped off, pure and simple, get it back now.
In the UK we have mobile repair people who come to your door, don't you have this? How old was your battery?, if over 5 years then it is a prime suspect, I did a bit on batteries a month or so ago, and don't want to ramble on again.
If it isn't the battery and still electrical it gets a bit more complicated but isn't rocket science, but you do need test equipment and knowledge.
To any of you out there, if your garage can't diagnose and fix in a month get it asap to another one who can, so many people are scammed because they don't know a bit of basic things about cars.
The first thing with no clicks is the starting circuit, you may have a parasitic drain flattening the battery, bad earths and a whole host of things, someone with skills needs to look at it.
Get it back, if it is worth it and get someone you trust to look at it