Matilda,
Good, you did discover what the IRS 1040 instructions said to do about DECEASED on the front page. You should still be able to have the refund applied to 2023, though, rather than receiving it yourself. Dig around a bit and see if you can force it. It is eminently doable when simply filling out a paper 1040. Also, did TurboTax explicitly tell you that you have to paper file? If you aren't receiving the refund, then you should be able to. Paper filing is only needed for Form 1310.
In the interim, I'll fire up my TurboTax and try to reproduce your situation.
