You need to copy & paste the system serial number from the "About This Mac" when clicking on the Apple menu.
It seems the vertical line character is most likely the letter "L" (aka "ell") since that is the only variation which produces a valid result of recognition since the number one and the letter "i" (aka "eye") fails.
If the digital copy of the serial number is indeterminate, then check the physical number etched into the bottom case of the laptop since it should be clearer and it should match the digital number. If they don't match, then your laptop has been worked on by someone who mixed up parts between two different laptops either accidentally or intentionally. Or if it was an official Apple repair involving the replacement of the Logic Board, then the tech made a mistake reconfiguring the system serial number which should have been caught when running the Apple service diagnostics after completing the repair.