Find the survivors of the Blarg attack and Buy infobot from scrap merchant were missions in Ratchet & Clank. Alonzo Drek had sent his forces to Oltanis under orders to destroy everything that moved, and didn't move, and to simultaneously steal the power generators for which Gorda City was famous. Failing to locate him on Gemlik Base they found a faster ship with the hope that they could catch up to him. Inside the ship was an infobot with a recording of Darla Gratch who commented on the destruction Drek had wrought, showing Ratchet finally how truly evil Drek was, causing him to apologize to Clank and the two to reconcile their differences.
Upon arrival they found out Clank was unable to accompany Ratchet due to the danger the continuous lightning storm posed to him, forcing him to search the city on his own for survivors with information on Drek. He eventually found Sam, a scrap merchant who had an infobot for sale, which Ratchet bought.
The Gadgetron vendor will now sell the Tesla Claw, a powerful weapon that acts similar to the Pyrocitor, but with better range, damage and an automatic target-seeking ability. It is quite expensive, costing 40,000 bolts, or 30,000 with the now available Persuader. When done, take the nearby platform to head the half-sunken plaza in the distance, from which you must take the central path, heading further into the city. A pair of scoutbots patrol here, shortly after which you will run into a group of plasmabots, who will come out of a hole in the ground. They are notable for their attack, which comes in the form of a rather long stream of electricity, that they sweep from side to side. Dodging one is harder without Clank, and due to their numbers it is best to either take them out from afar, or rush them when they appear and use short range weapons (such as the Walloper, Pyrocitor and Tesla Claw). Lastly, note that they will return to their initial location if you leave the vicinity.
Up ahead a minibomber will attempt to stop you you continuing by launching a constant number of explosives, that are relatively slow to detonate. Simply shoot it down, though it is rather durable, from a safe distance, then deal with the second group of plasmabots behind it. Behind that group is tougher set-up, involving one Minibomber and a third group of plasmabots, the former will largely stop close range approaches and the latter will, once they are set up, hamper long range maneuvers. The Decoy Glove and Glove of Doom can prove helpful here, or alternatively destroy the Minibomber with the Devastator or Visibomb Gun while the plasmabots are not yet (fully) active.
Take the nearby grindrail to the next area, which deposits you immediately upon another batch of plasmabots, forcing you to deal with them up close. Sweep past the scoutbots patrolling nearby and shoot down another Minibomber guarding a thin walkway, being careful not to fall off. Climb the ruins at the end, dealing with several more scoutbots and a lone plasmabot. A machinegun turret will be guarding the next walkway and afterwards you must clear a few more scoutbots until you can access a large three-sided grind rail.
Three plasmabots will follow you, periodically shooting their beam of electricity, forcing you to switch rails constantly. Partway through part of the rails will lead through an electric fence, forcing you to switch to a clear one, upon which a bolt thief will likely lay an explosive which must be dodged. Continue avoiding any barriers and mines to reach the end, noting the plasmabots will have destroyed themselves in the process. Move forwards to trigger a cutscene, ending the "Find the survivors of the Blarg attack" mission, and after talking to Sam, pay him the desired 2,000 bolts to end the "Buy infobot from scrap merchant" mission.