Two BSODs: 0xc000021a; SYSTEM_THREAD_EXCEPTION_NOT_HANDLED

My HP Envy laptop, running Windows 10, is stuck in the following infinite loop when I try to power up:

1. BSOD, error code 0xc000021a
2. Automatic reboot, "Preparing Automatic Repair" shows at the bottom of the screen
3. BSOD, SYSTEM_THREAD_EXCEPTION_NOT_HANDLED(iaStorA.sys)
4. Automatic reboot, everything looks normal until #1 happens again a few seconds later.

I cannot even get the system to the repair screen on startup. Repeatedly tapping escape brings up the menu, but when I type F11, system diagnostics, I get BSOD with error message DRIVER_IRQL_NOT_LESS_OR_EQUAL (I am not sure, exactly what; it only stays up for a few moments before spontaneously rebooting).

I need urgent assistance to get to the boot disk on drive D...somehow...any how. I cannot even get to the system repair!!

EDIT: I did a hard drive extensive test last night and set it to loop until error. It just completed two iterations, and though it has not found an error, the hard drive short and long DST checks have statuses of "warning." What does this mean?

Hi tollbooth,

If I am correct, DST means Drive Self Test.
With the status 'warning' my guess is that the hard drive is starting to fail.