Laptop: Latitude E5570

Description of problem:

I am trying to encrypt a Latitude E5570 with Windows 10 bit-locker.

I have updated the BIOS to 1.3.8 using the BIOS update on the web site to the latest version,

I followed the procedures described on the DELL forums & various web sites.

I have also initialised the TPM chip & cleared / reset the BIOS to factory defaults.

When the laptop restarts it prompts for the bitlocker password :-(

It does write the password to active directory.

 

Does anyone have any ideas?

I have bitlocked various DELL laptops in the past without any problems, it is this particular laptop is driving me nuts. DELL technical support told me to contact Microsoft who are normally as helpful as a hole in the head.

Thanks

S.