Hi Michael,
Thanks for contacting Syncfusion support.
We have analyzed your requirement for adding an existing image in a button. To use an external image inside Button control, you could use the PrefixIcon or SuffixIcon APIs available in button Plugin.
For your convenience, we have created a simple sample based on your requirement.
Please get back to us if you have any further assistance.
Regards,
Prem Kumar Madhan Raj.