Hello,
Long shot, but is this likely to support the DS-870?
In Windows, using Epson Scan 2 the button works assuming you opened EpsonScan2 first.
In Linux, using Ubuntu 24.04 the button doesnt work - eg open the EpsonScan2 gui, press the scan button and nothing happens. Naturally therefore I guess its not unexpected that its not working with es2button. After pressing the button the scanner shows checking jobs followed by a communication error type message.
I also tried the EpsonScan2 gui with the scanner attached to a network interface, but again no dice.