Zorin Core not booting

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Zorin OS 17 doesn't boot after installation, straightly boots into laptop boot screen

I installed Zorin OS Core 17 on the same laptop I installed 16.3 on. After reboot, it doesn't boot, instead it goes straightly into boot screen of the laptop. But when I went to run the installer again, it detects that Zorin OS 17 is installed. Please help.

Please see this post and help me.