I don't think the IRS will be a problem. The first year that penlties were applied for non-filing was 2015, so I think 2014 would have had to been filed in order to flag 2015.
A larger problem, but not yours, is that your client didn't file an annual report(s) with the SOS, which is required to keep it in good standing. The SOS maintans an on-line list with each corporation's status. If the corp is not in good standing, the bank might deny the loan and/or put more honerous conditions on the loan.
Ir is also possible that the corp has ben suspended. Suspended corp contracts are null and void.