Notebooks are pretty much all the same, difficult but not impossible to work with, that is a nice guide at your link but I would make a couple of other additions to the guidance;
1: Once the battery and AC adaptor have been disconnected, press and hold down the power on button for around 20 seconds to get rid of any residual charge.
2: Ground yourself by touching a radiator or anything else metallic resting on the floor, cooker or fridge etc.
3: Keep any different size screws separate so none can go back in the wrong place, I use the lids off aerosol cans for this.
While the notebook is opened up and the MB visible, inspect and clean the electrical contacts for the HDD, take care and do not use anything abrasive, please also see my edited picture below.