I just finished this hell today and have some additional tips to offer.
First, if you're looking for a full game walkthrough so you don't struggle with what to do or where to go during an area without enemies and lose your run over something stupid, check out this video below with commentary. It helped a lot, and I used a mix of his strategies and Kreeper's
-Practice the following until you master them: Marta Cart, every segment involving Nick & Laird, the Library, all of the Mines. The mines are not that bad once you know what to do and you were diligent about saving battery, you just don't want to blow it after getting this far so its worth it to practice. The rest are run killers and where almost every death of mine occurred.
-For Marta Cart, I used a modified version of Kreeper's strat. Follow what he does until you're pushing the cart the second time after running her through the bandage room. For me, I never had enough time to push it all the way before she would find me again. So push and wait for the scream, then run through the section of fence she broke down earlier. Run forward and loop all the way back around going the way you entered the area from. At some point you'll hear Marta bashing down another section of fence; this buys you the time needed to push the cart the rest of the way. I tried many strategies here and none of them consistently worked for me except this.
-Nick & Laird fucking suck. Over half my runs ended with an arrow to my face. First encounter, run forward to spawn them, then run back and enter the tent left of the fire from the BACK. Enter crawl status in the grass behind the tent, then forward into the tent. Stop about midway, do not go too far forward or Nick will grab you and kill you. When they pass the tent, crawl forward and run for it. Using the grass to go prone is key; if I did it outside the grass they were more alert and would sometimes kill me while I ran for it.
-Next pain in the ass N&L section is after getting the camera back. I strongly suggest following the strat here from the video I linked, with a slight modification. When you enter the house near the exit with the 2 doors, do NOT lock the first door (the one further from the window you will need to jump out of), only lock the second door. By doing this it forces Nick to use the unlocked door further from you instead of breaking down the door closer to you since the AI will always prioritize and unlocked door over a locked one. Stand near the window and look for the door opening, that's your cue to run to the exit. Forcing Nick to use the further door gave me much more time to make it the exit; I was killed 3 times trying to escape when he was breaking down the closer door, even though in practice it wasn't an issue.
-The Library is not as intimidating as it first appears. You can NOT be killed until you encounter the demon near the exit, so take your time fumbling around the maze to conserve battery. Try your best to memorize the path with practice and take it slow on your real run. Flick the nightvision on and off just enough to see where to go. When you get to the desk with the battery, walk toward the light to spawn the demon. At this point leave the camera on until you enter the crawl space.
Battery Saving Tips:
-A huge overlooked tip is adjusting your TV's settings to brighten the game up. Max out brightness and contrast. Poke around in your settings for additional things like gamma settings, black levels, dynamic contrast, and experiment with them to brighten the picture up. I game on an OLED and had access to all of these and could also crank the OLED light up too. Max out the in-game gamma meter too. The game will look like a hideous grey mess, but this made a massive difference with visibility, with only a handful of spots being in total darkness.
-Saving battery in the beginning doesn't matter. When you get the camera back after N&L take it the battery will always be at 60% no matter what. From this point on you need to conserve.
-First school section before the lake, you will be in total darkness with Jessica talking in the background. Use only the microphone, no night vision. The microphone does not drain the battery. There's no enemies here so take your time and use the mic to follow Jessica's voice in the right direction.
-You shouldn't need any battery until the pool section right after the raft. Use night vision to line yourself up with the lines on the pool floor, turn off the camera and then run straight ahead while mashing A. Once you reach the pool's edge you'll pull yourself up with almost no battery used.
-The Library, as said earlier take it slow in the maze and just flick the nightvision on and off to see where to go. Memorize the route for minimal battery usage. When you encounter the demon, keep it on until you're past him. It's not worth losing your run here trying to nickel & dime the battery, you'll have plenty for the mines.
-You'll need about 40% battery to comfortably get through the mines. I went in with 50% following the above. If you're tight on battery, try not to use any until you have to deal with Val. The first enemy encounter is pretty easy to do with no battery following Kreeper's strat. Walk backwards to the encounter and wait for the music cue, this will help you get back up without having to use battery to orient yourself.