How to auto populate a sharepoint list data connection to a infopath form

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Hi I am trying to create a form in InfoPath that will be added to the Forms library in the sharepoint. I want to auto populate information from a Custom List to the form.

for example:
if I type a serial number the info such as item name, manufacturer, date of purchase, etcetera will automatically reflect in the form. the data are all in the SharePoint Custom List.

Kindly advise.

What I have tried:

I have tried to using From Web Service but I cant figure out the formula to use