I have an XPS 8500 and I can't update the BIOS to A14.  I couldn't update to A12, either.

I have tried using SupportAssist as well as downloading the update file directly from Dell support.  Neither way works.

The PC is updated otherwise, with all the most current Win10 and Dell driver updates.

When installing, I receive the following messages:

1) Error! - Delete Temp File Failed

2) Update BIOS - Parameter Error! (this one comes up twice)

I would just leave my PC alone, but it sometimes has issues with sleep/wake up/powering down and I think the most current BIOS would help.

On a similar note, I cannot restart the PC and enter any type of Safe Mode or open into the BIOS by using any method.

Anyone have any advice?