Holy Crap!! I didn't think we could get it to work after almost trying everything and doing a bit of searching around on that error message. Glad to have helped you out mate! It was getting a bit frustrating not getting it to work all the other ways.Success!
Using the latest method you describe there was another Epson-2710 file right at the top of the list which I installed and now it's working. Thanks for your help mate.
ii imagescan 3.63.0-1epson4linuxmint19 amd64 next generation image acquisition utilities ii imagescan-plugin-gt-s650 1.0.2-1epson4linuxmint19 amd64 Image Scan v3 GT-S650 Interpreter Plugin ii imagescan-plugin-networkscan 1.1.3-1epson4linuxmint19 amd64 Network scan plugin ii imagescan-plugin-ocr-engine 1.0.2-1epson4linuxmint19 amd64 Image Scan v3 OCR Engine Plugin
sudo apt-get remove imagescan imagescan-plugin-gt-s650 imagescan-plugin-networkscan imagescan-plugin-ocr-engine sudo dpkg --purge imagescan