New Hyundai owner-unhappy

I am new on here and hope I can get some answers about my 2014 Hyundai. I just bought it 1 1/2 years ago and I notice random things, brights/lights acting funny...almost like a short, same with the windows, then my car wouldn't start, no crank no click....it was very subtle at first so I thought it was just me. 2 weeks ago I took it for a diagnostic( Hyundai dealer)...nothing found, the next morning(Saturday) I got stranded for 10- 15 minutes because the car would not start, the dealer said they couldn't help me unless it happens while on diagnostics, that Tuesday went out, click, click....nothing, took it to the dealer where I bought the car, they said it was the battery and that I should have no more issues, went o get in my car (at the dealer) no click no crank, the service advisor tried twice, same thing. They have had the car a week and the said it turned over fine with no issues except once but it did try to turn over.....said they probably could not help me unless it goes out completely. Now I am stuck and in shock that I am completely helpless knowing my car will break down somewhere.... This is my 1st Hyundai and may be my last/

 

Hyundai is notorious for bad grounds.
Clean battery terminals .. positive and negative
Clean the grounding points on chassis.
Negative battery cable goes under battery tray .. so must remove tray to get to ground strap
Clean body paint and rust off and reset the ground strap
Do the same with the engine ground strap.
Check/inspect the cable ends near the terminals
If corroded or dis-colored then clean with wire brush
Then the only other place that could cause this kinda trouble would be the ignition switch
Hopefully not that and this fixes the problem