ASRock EPYC3251D4I-2T can't boot with IBM M1015 with clean flash

[nagl23]

I'm following this guide to reflash my IBM M1015 card to IT mode: https://www.servethehome.com/ibm-serveraid-m1015-part-4/

The motherboard is EPYC3251D4I-2T

After completing this step

megarec -writesbr 0 sbrempty.bin
megarec -cleanflash 0
<reboot, back to USB stick >

I can't boot. The system hangs on

DXE--PCI Bus Enumeration...

message before I can pick a boot option or enter UEFI setup.

When I remove the card the system boots normally, but without the card I can't finish loading the new flash.

How to proceed with this?

 

[nagl23]

PROTIP: Don't try to bypass this issue by hot-plugging the pcie card after boot sequence is completed - you will likely fry your card.

I've ordered another IBM M1015 card, will try to flash it on another machine next week.