Remove the 4 screws on the stand
Remove the 2 side panels and screws circled
Remove the 2 remaining screws under side
Once all screws have been removed the back plate can be removed from the screen.
It’s held together with clips, we used a flat head screwdriver turning it sideways to lever it open, starting at the bottom. Once you get a few clips off the cover should pop off.
The RAM sticks are located at the top, unclip the existing and insert new stick. To re-attach the case just push together, it will clip back in. Test the till starts up before putting all screws back in!