I want to just add a submit button to the standard detail page. This is distinct from edit button. Before the user can submit, I want to enforce some validations.

So when I click the submit button, I want to change the status field to 'submitted' in the background,  which would fire a bunch of validation rules making sure certain fields are filled out.

The following VF Page is attached to the submit button shows the first validation error at top of the page..

.However, I would like to get to the page that would simulate the following; User clicked the "Edit" button and set the status field as submitted and tried to save the record, they would see a bunch of validation errors right next to the field. If that is not possible, I would like to atleast all the validation errors at the top of the page. Currently I see only the first one.

<apex:page standardController="CAPA__c" extensions="submitCAPAController" action="{!redirectToSubmissionResult}">
<apex:PageMessages />
<apex:detail />
</apex:page>

public with sharing class submitCAPAController {

       private ApexPages.StandardController stdCtrller;

       public CAPA__c CAPA {get;set;} 
              
       public submitCAPAController (ApexPages.StandardController stdController) {   

          stdCtrller = stdController;
          CAPA = (CAPA__c)stdController.getRecord();       	
       	
       }     
       
       public pageReference redirectToSubmissionResult() {
       	    
       	    CAPA.Status__c = 'Submitted';
       	    //stdCtrller.save() doesn't seem to get to the right page. 
       	    try { 
       	    	update CAPA;
       	    } catch(DmlException ex){
                ApexPages.addMessages(ex);
                return null;
            }
            return null; 
            
       }
}