Fairphone had to switch their display module supplier somewhen. OS and firmware versions this old don’t support the newer display modules.
I’ll assume you have one of those.
Did you backup your Internal Storage files, too?
Because a TWRP backup will not include the Internal Storage.
If my assumption about the display module is correct, it could seem as if nothing happens, but Fastboot Mode should still work.
Please check whether rebooting or starting the phone while keeping Vol - pressed gives you Fastboot Mode … you would have to check with fastboot devices on the computer.
ADB doesn’t work in Fastboot Mode, and the fastboot command only works in Fastboot Mode.
If fastboot works, you could install the phone from scratch …