AnshuGoel

The measures can be ranked in the following order in this case:
CES, C-SAT, NPS, Churn, CAC. 
 
The customer who is in possession of an electronic product, looking for an after sales service will do so in  case an issue occurs in the product, so the first thing he would be concerned with is the efforts required to get that issue resolved. If it is easier for him to get that issue resolved, he is more likely to be loyal in the long run towards the brand and product range in that brand. Hence CES should be the first measure. 
The second concern is how is that issue solved and whether it is solved in accordance with customers expectation. Hence C-SAT is the next measure.
If a customer feels that it is easy for him to resolve issues and that his issues are resolved up to his expectations he is more likely to be loyal to the brand and its offerings and hence NPS and Churn (In case the customer is not satisfied) comes. CAC , I feel has limited significance in this case and hence have ranked it last.