How can I recover my AT&T sim unlocked Blackberry Priv after it was wiped while autoloading?

I attempted to autoload marshmallow OS using an AT&T file while I had a non-AT&T sim card in place. I eventually noticed a repeated sequence of flashing led lights, white to green to yellow to green again. The device has since been unresponsive to any button combination. It clearly would need something external if it is to be repaired. My subsequent research tells me I should have placed the AT&T sim card in first. Unfortunately, I am now not able to get it into the fastboot mode so the autoloader does not recognize it.

have you called your carrier? sounds like the phone is toast. Maybe they can tell you if loading an OS is possible now. Or maybe they can give you MM for your phone?

By calling the carrier I take it you mean my local carrier. My local carrier probably would not be able to help but I will try them.

I do not think AT&T would help because the phone is sim unlocked and I do not have an AT&T account.

I will try my carrier and let you know.