In the old days when Apple did provide their operating systems on DVD, you would restart the mac and press and hold the Command and C keys to boot from the DVD. What instructions do you have from the reseller of this bootleg DVD on how to
get Lion installed.
How to reinstall macOS from macOS Recovery - Apple Support you can follow the instructions in this guide
but given the number of people that are having problems with this recovery service it may not in fact work.
Do you have or can you borrow a mac that you know can run El Capitan, if so instead of installing Lion you can try and install
El Capitan. If so follow the instructions below, you can then use the resulting bootable USB installer to install
Mac OS X El Capitan on your MBP.
How to upgrade to OS X El Capitan – Apple Support
At Section 4 download InstallMacOSX.dmg. When that has downloaded open it and you will get InstallMacOSX.pkg.
Double-click on that and an installation window will open, this will convert InstallMacOSX.pkg to the
Install OS X El Capitan.app which will be in your Application folder.
Use the Install OS X El Capitan.app to create a new bootable USB installer, How to create a bootable installer for macOS – Apple Support
Please note you can only convert the InstallMacOSX.pkg to the Install OS X El Capitan.app on a mac that can install El Capitan.
Therefore if your mac came with macOS Sierra, macOS High Sierra, macOS Mojave or macOS Catalina pre installed you will not be able to convert the InstallMacOSX.pkg to the Install OS X El Capitan.app.