2015 Hyundai Accent randomly won't start

Hi my daughter's 2015 Hyundai accent
randomly doesn't start. But then a few hours
later it will start no problems . We have had it
to the Hyundai dealership they were stumped
said they got corporate and their engineers
involved and can't figure it out.  They ended
up putting a new starter in but it had gotten a
new starter a year ago made zero difference .
Brought car home and it did it again the next
day . After car sits for a few hours starts up
just fine.  Battery is good & no clicking noises
happen.  Took it back to dealership they had
it over a week & could not reduplicate it not
starting , we took it home and next day guess
what? Didn't start. Doesn't happen at any
specific time . Car isn't driven many miles .
Someone please help ?? Anything at all I can
suggest to dealership? You'd think since
Hyundai service knows these cars that
someone would be able to figure it out