Please also see this TurboTax FAQ for error message that come from an IRS reject of your employer ID number:

https://ttlc.intuit.com/replies/5660674

If you are still unable to correct the employer ID field and you have NOT already e-filed your return, then you should go back in under Wages & Income and delete the W2 that's causing the problem. After deleting it, you can click in to add a W2 again.