I have had this bike for 3 weeks and experiencing the same issues..Shut off 7x in a 15 k ride really annoying.. Phone Giant Twickenham for some advice following reading this.. They didn't seem to be aware of any issues..
Took it back to Rutland cycling Milton Keynes who seem keen to help. I really don't wont to carry on with hassle love the bike ..Shame about this issue
Thinking about Specialized VADO sl 5.0 2020 would be interested to know where you ended up..