Reana Clio 1.6 2001 failure

Hello,
my car has been having the same fault for a long time, it does not turn on, it does not make contact, according to the mechanics there is a failure in the barrier sensor and according to others there is not even the departure sensor reviewed the injectors and the battery but nothing, logically I have no idea of ​​mechanics, perhaps an help so that when I take it to the mechanic they do not continue to lie and that they charge me for something that is going to be bad for something that is going to be bad

Doesn't make contact? Or does it not start?, if it does not make contact, it does not turn on the board or anything is the current failure from battery into the interior and its waters, if it does not start checks that reaches the battery and sheet meter luck