IPHONE 6 no power

I have 2 iphones 6 with no power,
I tried in computer but pc doesnt detect iphone
I tried different charging port but still its not working
I have tried different battery but still it wont turn on.

I have tried with external power supply and amperes are always 0.2A, when I press power button then nothing happens in the phone and ampere still remain same when I press button from external power supply.

what could be the problem?
whats the solution?

Thank you