Accidentally updated to El Capitan on unsupported Mac from Yosemite; stuck on flickering logo

[Yuurei]

Somehow, I accidentally updated to El Capitan on my 2007 mac from an already unsupported Yosemite. Now, whenever I boot my macbook, I am taken to the logo screen with a flickering Apple (there's a box with a question mark that flickers behind the logo).

I've been looking for fixes like booting with Command + R, Command + R + P and single user mode, but it all takes me to the same screen.

Is this the end for my macbook?

 

[Nermal]

You won't have Internet Recovery on that machine, and it sounds like you've managed to replace the recovery partition with an incompatible one. It's not insurmountable but you'll likely need to reinstall a supported OS from its DVD.

 

[maflynn]

As @Nermal stated. The recovery partition won't help you and you don't have the internet recovery so your only option is to boot off your original DVDs and reinstall that version of OS X.

Hopefully you have a backup, as with doing any OS upgrades (or downgrades), its best to have a backup of your data.

 

[n-evo]

Install OS X (the one that came with your Mac if you don't have anything else) on an external drive, retrieve all your data and reinstall OS X on the internal drive.

 

[RAMtheSSD]

I would use target mode to get the data out (option+t when restarting) while you would need a friend with a Mac, any Mac will do. Still, to make things easier, stick with Macs with a firewire port (you have a 400 mb/s right?) rather than thunderbolt. Afterwards, reset the pram after restarting and put in a DVD and use option+C and then plug in your RJ45 and that should do the trick. It doesn't matter if the OS disk you have is Snow Leopard (I don't know if earlier cats work), the machine will install the latest OS it will support.