What version of windows 10 do you have--Home, Pro or Enterprise? Did you reinstall the correct version? Home does not have bitlocker and comes on most new computers. Make sure you did not install that if you originally had Pro.
The TPM on my XPS 9560 disappeared a while back, maybe sometime last year. I forgot the exact details but I had problems with Bitlocker not finding the TPM and the TPM option had disappeared from the BIOS configuration menu.
I setup Bitlocker to use a password at startup instead of TPM and that has been working fine for me.
However this morning I upgraded the BIOS from 1.15.0 to 1.16.0 after being prompted by Support Assist but afterwards had the same BIOS message at start-up "Alert! TPM device is not detected".
I downgraded to 1.15.0 and the message has stopped.
I am not particularly concerned about the "loss" of the TPM, but I would like to now is there a way to disable the check to get rid of the message.
Same here with Firmware 1.16 Update. I had to downgrade to 1.15.
You don't have to run it from a USB boot.
Download XPS_15_9560_1.15.0.exe and save it where administrator can access it (for example: Public Downloads).
Log on as admin and run it from within Windows (10 Home for me). The same way you normally do. Follow the instructions ("Don't turn off the power etc..").
The error warning's gone but you get the update notification back in Windows instead. You have to click "Remind me later".