The Diaries of the Dead side quest in Dead Island 2 can be acquired from W.O. Rodriguez after completing the Cremains of the Day side quest. You’ll find her in the military tower located in the northwest of Venice Beach.
Where to Find the Memory Stick at the Convey in Diaries of the Dead
After picking up the quest from W.O. Rodriguez, head down stairs and turn left at the bottom to use the push switch and open the shutters. You need to head southeast out of the military compound and onto the beach, where you’ll find the convoy that Rodriguez spoke of. There will be a bunch of zombies in the area that you’ll need to deal with, then look for the memory stick in a laptop behind the central truck here.
Kill the Signal Officer for the Comms Area Keycard
Once you pick up the memory stick, you’ll be attacked by multiple waves of zombies from different directions. Rodriguez will communicate with you by telling you where they’re coming from at different points, so pay attention to her and take out the zombies as they arrive. Most of the zombies will consist of regular enemies, but there will be some elite crushers mixed in occasionally. At the end of the attack waves you’ll see a zombie named Signal Officer, who has the Comms Area Keycard that you need. Kill him and loot it from the corpse.
Reach the USMC Comms Area
Now that you have the keycard, head south to the USMC comms area and turn left once inside. You’ll reach a keycard reader that you need to use to enter an area with a satellite dish, which you can use to upload the fallen soldiers’ letters. After interacting with the dish, you’ll need to wait a while for the upload, and during this time a number of zombies will attack you. Among these is a mutated zombie named Lt. Bryant. This is a fairly tough zombie with a long reach in melee attacks, so try to keep your distance while using ranged attacks, and be ready to dodge or block when he’s close. You’ll need to slowly whittle his health down as you go here, and try to kite him around the nearby objects if you need to create some distance.
The attack will soon end as you discover that the upload has failed. Interact with the satellite dish again to advance the quest, then make your way back to Rodriguez at the tower in the northwest of the map. After speaking with Rodriguez again here, the quest will complete.