Dead Lenovo Small form factor IdeaCentre 310S Desktop PC restored to life!

Sometimes machines come in to the workshop locally that aren't the usual Macbooks; while often it's not economical to try do board repairs on these machines, sometimes it's worth having a 15 minute look in the case of it being something obvious. In this situation, the board on the first glance looked perfectly clean, no bugs, no liquid damage, no lightning or surge damage, so what could it possibly be?