MBP bootable usb problem (flashing questionmark folder)

Hi everyone,

I am a Mac user since half a year now and I was very happy to be until 3 days ago when my MBP apparently crashed. I already searched for similar cases online quite much but it didn't help me so far as my problem is pretty specific I guess.

It first showed a few minor issues during startup, had to try it twice before it actually started up (it showed: 'Your computer restarted because of a problem'). When it did I ran First Aid from Disk Utility on both drives but it did not show any errors. Then used the MBP to watch a movie, shut it down, battery was near empty so I connected it to the charger, went to sleep, next morning the MBP did not start up anymore. It only showed the flashing questionmark folder.

Since then I tried recovery start up. Regardless of which key combination I use, it only goes to Internet Recovery (basically meaning that the recovery partition is damaged?). Internet Recovery times out on the 2100F or 2106U error after a while. Probably due to the very slow internet connection that I am using.

The only option I thought remained possible was to try and boot it with a bootable USB drive. So I downloaded a zip file containing MacOS 10.12.5 on the Windows computer I have (download took over 2 days). And made a bootable USB drive based on this guide (with InstallESD.dmg derived from the zip file): http://www.intowindows.com/create-macos-sierra-bootable-usb-drive-from-windows/

I followed the exact steps shown in the guide and tried to start up using holding C after the startup chime. It only proceeds to the flashing questionmark folder. I tried it using the other USB ports as well, same result. Then I tried starting up holding the option key but it only want to start internet recovery that way, I have no possibility of choosing a start up drive. I think it doesn't recognize the supposed to be bootable USB.

I've searched a lot on why the bootable doesn't work but I can't find anything useful. I also searched for other ways to create a bootable but other ways only seem to be made for installing MacOS on a Windows PC, like Hackintosh stuff.

Can anyone of you please advise me on what to do? Preferrably on how to make the (or any other) bootable work.

Some additional information:

- MBP type: 17", Early 2011

- I have been using MacOS 10.12.5 (Sierra)

- Previous owner replaced the original HDD to an SSD (Samsung EVO 250GB if I remember coorectly)

- After purchase I swopped the Superdrive for a 1TB HDD SATAII

- All worked well for months

- I am currently on a vessel with only a very slow satellite internet connection and only a Windows computer to work with

- I have a recent TimeMachine back up but it's at home so I can't access that for a few weeks

- I don't see Internet Recovery as option due to the low speed connection (it times out) and obviously I can't run to a genius bar for the next few weeks.

Any help is much appreciated!

Thanks in advance,

Eric

PS: I hope I posted this in the right community, I couldn't found a better suited one.