Before I explain my problem, you should know that I have very little experience with Apple products. I've never used an IPhone and have rarely used an Apple computer since the 90's and this is my first experience with an Apple laptop. If you don't wanna read a whole orgin story, you can skip the next paragraph.
My sister gave me her Mac Book Pro a1398 to get some files off of it for her 6 or 8 months ago. She told me that the laptop wasn't working anymore. Actually, before she gave it to me, we tried to take it apart at her house to get the hard drive out. We removed all 10 screws from the bottom cover and(if I remember correctly) it still wouldn't come apart, so we gave up. I think she told me she brought it to an Apple store and they weren't able to help her. I can't remember everything we talked about regarding the laptop, but she said the last time it worked was when it was plugged in to the wall during a storm. We assumed it was fried by lightning. I tried to turn it on after she gave it to me but it wouldn't turn on. She couldn't find the charger that came with it, so she gave me another one from a different Mac Laptop, but it wouldn't plug into the port because the connector wasn't quite the same. The metal around the pins wasn't quite the same. So I was waiting for my sister to find the charger that came with the laptop, but she never did and because we thought the laptop was fried we just forgot about fixing it.
Last night I was tired of looking at the laptop in my bedroom everyday and decided to modify the connector to get it to fit in the port(after making sure the connector specs and the laptop specs were the same) to try one last thing before giving the laptop back to my sister. I used my father's grinder wheel to grind some of the metal off until it fit. And to my shock, after charging the battery, the laptop turned on! But it didn't boot up. You just see a blinking folder with a question mark, which means the hard drive isn't detected? I followed the instructions on this page to try to fix it except for trying another start-up disk since I don't have one. Those instructions are a little confusing because one of the solutions is re-installing the OS. But you can't install the OS if the hard drive isn't detected. When I boot into recovery, I go to Choose Startup Disk, but there's no disk to choose. When I go into Disk Utility, you see disk0 and OS X Base System treed from that. Is the recovery partition on the HD or somewhere else? The only thing in the list on the above page I haven't tried was Disk Drill because I can't install it. When I run the command to install it (sh <(curl http://www.cleverfiles.com/bootmode/boot.xml)) , it says: curl: command not found. I guess that means that the Linux distro that OSX or the recovery partition uses doesn't have the curl command(Which I've never heard of before), or it's a newer command. Is there anyway to install Disk Drill on the laptop? Is there anyway to get the hard drive working that I haven't tried? Is it possible the just the hard drive or the circuit board it's connected to got fried by the lightning? Getting the laptop working except for the hard drive has me completely confused as to what's actually wrong with it. I haven't told my sister yet that I'm working on her laptop again. Maybe the only thing to do is for my sister to bring the laptop to an Apple store?