Unbricking APM Mustang

Firmware update usually ends well. Previous (1.15.19) firmware failed to boot on some of Mustangs at Red Hat but worked fine on one under my desk. Yesterday I got 1.15.22 plus slimpro update and managed to get machine into non-bootable state (firmware works fine on other machines).

So how to get APM Mustang back into working state?

X-Gene Mustang Board
Boot firmware (version 1.1.0 built at 12:25:21 on Jun 22 2015)
PROGRESS CODE: V3020003 I0
PROGRESS CODE: V3020002 I0
PROGRESS CODE: V3020003 I0
PROGRESS CODE: V3020002 I0
PROGRESS CODE: V3020003 I0
PROGRESS CODE: V3020002 I0
PROGRESS CODE: V3020003 I0
PROGRESS CODE: V3021001 I0
TianoCore 1.1.0 UEFI 2.4.0 Jun 22 2015 12:24:25
CPU: APM ARM 64-bit Potenza Rev A3 1400MHz PCP 1400MHz
     32 KB ICACHE, 32 KB DCACHE
     SOC 2000MHz IOBAXI 400MHz AXI 250MHz AHB 200MHz GFC 125MHz
Board: X-Gene Mustang Board
The default boot selection will start in   2 second
Shell> fs6:
FS6:> ls
Directory of: FS6:
08/04/2015  00:28              39,328  UpgradeFirmware.efi
08/27/2015  19:20                  56  apm_upgrade_tianocore.cmd
08/27/2015  19:20           2,098,176  tianocore_media.img

And your Mustang should be working again. You can also try to write other versions of firmware of course or grab files from internal hdd.

aarch64 fedora mustang ubuntu