I had the same issue, for me updating the TPM firmware solved the issue (but it is convoluted) https://superuser.com/questions/1668861/alert-tpm-device-is-not-

I had the same issue, for me updating the TPM firmware solved the issue (but it is convoluted) https://superuser.com/questions/1668861/alert-tpm-device-is-not-detected-on-dell-laptop-boot https://superuser.com/questions/1668861/alert-tpm-device-is-... My guess is that Dell didn't update the TPM firware, my guess is this breaks some keys so can't be done automatically and a BIOS update at some point then screws up the handshake with the older TPM firmware unless the laptop is fully powered off. But I'm not a huge fan of dell hardware.