Pentax 70S issue

Buongiorno!

I’ve picked up a Pentax 70S a few years ago for 3€ at a Dutch thriftshop. Great deal! But at some point it was acting weird so I stopped using it. Now I moved to Milan and love doing street photography here. I brought this one along, changed the batteries and gave it another go. It was working perfectly for 1 roll, but when I shot 16 photos on a new roll, it suddenly stopped. It gave an E, but was able to turn off and on. It didn’t do anything. So I had to take rewind the film and develop only 16 photos.. I want to know what this issue is and if it’s easy to have it fixed; worth it to have it fixed. The pictures actually turned out well so I still want to use the camera. Any tips are welcome and please share your experience with this camera!