rejection

my e-file was rejected due to my mothers taxes claimed me as a dependent and it shouldn't have. I didn't know about this. I have no correction to make. Do I have to print my taxes and send in now? I don't owe  any taxes and I am not getting a refund. I only had a half year of unemployment. Do I even need to file? And when I don't owe any taxes can I be charged any fees for being late? I filed an extension on time and was accepted. I filed my taxes before the extension date but I didn't learn of the rejection until now. It says we have until the 20th. Is that midnight on the 20th? or midnight on the 19th.

Thank you