if you want to change created/By fields on target list you will need to remove their ReadOnly flag first

SharePoint: Modifying Created By field in SharePoint using web services and SPServices | SharePoint Learn… 

I am calling web service to update the Created By field to 'Read only; Any thing wrong with this code, i am getting 'The remote server returned an error: (500) Internal Server Error.' error . Please help

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/sharepoint/soap/">
<soap:Header>
</soap:Header>
<soap:Body>
<m:UpdateList>
<m:listName>InputReferrals2017</m:listName>
<m:listProperties></m:listProperties>
<m:newFields></m:newFields>
<m:updateFields>
<Batch OnError="Continue">
<Method ID="1" Cmd="Update">
<Field ReadOnly="FALSE" Name="Author" />
</Method>
</Batch>
</m:updateFields>
<m:deleteFields></m:deleteFields>
<m:listVersion></m:listVersion>
</m:UpdateList>
</soap:Body>
</soap:Envelope>

I guess you have 2 issues in your request

1. as far as I can see in web service reference, the action to perform should be defined by a <Fields> node instead of <Batch>

2. I'm not sure, the field to update specified this shortened way is sufficient. all the examples I've seen used full field's definition.