TKRI Nanggala-402, carrying 53, vanished in 2,300ft waters near Bali this week
Rescuers found items including grease bottle for periscope and prayer rugs
Scan located submarine at around 850m (2,800ft) beneath sea, said military
Submarine now declared as officially sunk with no hopes of finding any survivors
Officials said oxygen supply on missing KRI Nanggala ran out early on Saturday