Returning ADP refunds to opt for a QNEC

[fiona1]

Employer fails ADP test.

Employer issues excess contribution refunds to HCE's.

Refund checks have been cashed.

The employer now wants to use the QNEC provision in their plan document to raise the NHCE average to pass the test. They use the current year testing method. Is this an option if refund checks have already been cashed? Can the HCE's send that money back to the plan?