15min delay before POST

Hi,

I have a Dell Latitude E6510. It worked just fine, but after changing the hdd to an ssd, after pushing the power button, all I have is a blank screen for exactly 15 minutes, after which I get the usual BIOS screens, and the system boots as if nothing has happened. I have also reviewed and changed some BIOS settings.

I have flashed the BIOS, but before that, I had a problem of the BIOS settings resetting to a previous value.

It seems to me, it is some kind of timeout, waiting for some non-existent hardware to be ready. Probably as I replaced the hard drive, a connection got loose?

Please advise me, could this be a faulty BIOS setting? Maybe some security measurement? If it is a missing hardware, the BIOS is waiting for, how could I pinpoint which is it?

If anyone from Dell reads this, could the 15min delay be any clue? Is it a BIOS feature that emerges only in certain situations?

The boot menu "Diagnostics" reports no errors.

The BIOS logs accessed through the BIOS setup menu show no errors.

Things I have tried and did not work:

- use the old hdd -> the 15min delay is still there

- load defaults in BIOS

- disable what I could in BIOS

- re-flashing BIOS

- removing and reconnecting BIOS battery

- booting without the laptop battery

- booting without any hdd

- booting after removing one of the memory modules

- installing windows is possible, after installation it works fine, but after a restart, it cannot boot anymore, dies with a flash of blue screen, then after a while a "startup repair" is loaded, which searches for problems, and but cannot do anything

- ubuntu works all the time

- using different hdds - I have tried 3 hdd-s, all of which worked fine in other machines.