Ei System 4430 model no.mid2020 Notebook 8640sc changing memory?

Ei System 4430 model no.mid2020 Notebook 8640sc changing memory?
I have had my notebook 8640 tested on the net for memory upgrade, and bought new memory, there are Two memory slots, But I can only find one on the underside of laptop, Where is the other one, any Help would greatly be appreciated, also where can i obtain manual/service for this machine, as i have brought recently, with no instructions/manual