After entering the Ishimura, stop in the bathroom and grab items and Power Node sitting about. Down the hall you'll be attacked by a Brute. The Plasma Cutter actually works better than the Ripper for this enemy, so combine it with some stasis shots to take down this beast. Don't run too far down the hall as it will trigger a second Brute along with other Necromorphs.
Take out each enemy one at time. Fight with precision, as rushing will simply get you swarmed by the onslaught. When the zone is cleared, search for more Nodes. Next hack the lift and ascend to the higher level.
Buy whatever you need from the store and press on. There are a lot of Pukers, Slashers, and Lurkers roaming around, so be on your guard when slaying them. After taking them out, search the area for another Node.
you'll now enter a zero gravity area along with a centrifuge puzzle. Stop first to look for a Force Gun schematic floating around the room. To solve the puzzle and reinstate gravity, find the pieces around the room. Each section of the centrifuge has a winding tube; align these tubes to allow power to flow.
After completing this task, return to the way you came from. Upon reaching the decontamination room you'll be attacked by more Necromorphs. Use stasis and explosives to deal with them quickly.
Take the next elevator and you'll arrive at the medical center. Grab what items you can and blast the Necromorph threats. Stop in the lab to grab another Power Node. You'll need to kinesis a few platforms to make it down below. Here, remove the battery to recharge the lightning surge in the middle of the room.
Upgrade your weapons at the Bench and grab the Power Node. You can use it on the nearby locked door, though only items are inside. Continue on to enter another zero gravity tube. There are Lurkers in here, so be sure to zap them while moving down the straight path. There is also a Power Node you can grab in here.
The next area is crawling with Stalkers and other nasty Necromorphs. Move slowly and stasis each one before taking them down with your Ripper. You'll zone arrive on the bridge, where you can start up the gravity controls. After messing with the terminal, enter an escape pod to return back to the Sprawl.