The flashing folder means that your MBPro cannot find a partition with a bootable system.
That can mean that:
Your hard drive is failing, or has already failed.
Or, there is some corrupted boot files in your system
Or, that you have unsuccessfully tried to install another system, and that failed to complete.
Many times, using another OS, such as Windows, to create an OS X bootable partition just does not give you a usable bootable installer for OS X.
Best choice is to use a different Mac, if you have access to one.
Have you tried booting to your Internet Recovery system? Restart, while holding Option-Command-R.
You should see a spinning globe, showing that you are booting through Apple's servers.
It can take several minutes before the boot completes.
Run Disk Utility then, and select your hard drive, then click First Aid.
If that passes - Quit Disk Utility, which will return to the main menu screen.
And, choose Reinstall OS X. That will install Lion (probably), OS X 10.7.5
If that installs, then boots successfully, you can continue on to download and update to El Capitan, if you like.
Chances are good with a 5-year-old drive that the drive has failed, and you will have verified that by this time.
You can fix by replacing with a new drive - or even better, replace the hard drive with an SSD for better-than-new performance.