Delete the W-2 and only enter the W-2C. Be sure to enter it as a W-2C
Yes, edit your original W-2 entry to include the Box 12 amount. This will make the necessary corrections and you will be ready to file your return. TurboTax knows exactly what to do with that amount.
Do not enter a W-2C in the software since it is not available or used for filing a tax return.
I can't only enter the w2c; it has no boxes filled in except for the Box 12 "C"
Form W-2c: Corrected Wage and Tax Statement is a corrected version of your W-2.
If you already imported or entered your W-2 and you haven't yet filed, go back and edit your W-2 with the corrected info from your W-2c.
If you already mailed your return, or it was accepted, you may need to amend.