nerf I wondered about Nel's focus on the phone in the kitchen and thought of a possible reason
I wondered if it was the phone in the kitchen that had been used to call for help. I will need to go back to Moller's testimony to see what numbers were called from. Nel could argue that OP didn't call for help upstairs, as the phone was habitually left downstairs and was on charge.
Of course, defence could argue that OP only put the phone on the charger once he was down - perhaps the battery was low and he wanted to recharge to phone the various people he phoned?