Inspiron 13 - 5368 - Win 10
Had it serviced by Dell (new motherboard).
On return, it always boots automatically to the Diagnostic Tools on cold boot (not on Restart) and starts the bevy of tests.
I cannot figure out how to take off this auto-boot. Nothing in the F2 Setup screen does it, not General-Boot Sequence, not General-Advanced Boot Options, not SupportAssist System Resolution.