Rename xml filename using the value of an xml-node

I already searched in the forum a way of renaming but I get all sorts of renaming and not the one needed. Change the XML file name using one of the nodes via Batch file (or PowerShell. It is for Windows)

I have a XML file named PO_BLABLA01_XXX.XML and I want to rename the file using a Batch File, making the file name being the PO Number "12345"

So having this content:

<Seller>
 <Name>POV AGING LIMITED</Name>
 <PO_No>12345</PO_NO>
 <AddressInfo>
   <agrlib:Address>ALBANY ROAD</agrlib:Address>
   <agrlib:Place>DESBOROUGH</agrlib:Place>
   <agrlib:Country>United Kingdom</agrlib:Country>
   <agrlib:Phone>9999-9999</agrlib:Phone>
 </AddressInfo>
 <VatRegNo>8888</VatRegNo>
 <BankAccount>7777</BankAccount>
</Seller>

I need my file to rename from "PO_BLABLA01_XXX.XML" to 12345.XML that is the value of the < PO_NO > field.

Can anyone point some light for me to follow :) Thanks!