Optiplex 5055 RyzenBIOS Faulty (not upgradable) 1.5 version upgrade

[LaszloE]

I have a Optiplex 5055 SFF Ryzen. I would like to upgrade my 1.5.0 BIOS to the latest (in this case 1.15.0).

What I think is the problem, that there was critical bug (issue) in version 1.5.0 and it cannot be upgraded or downgraded anymore.
Side Note: Dell "retracted" version 1.5.0. You cannot downloaded from the old versions.

When one wants to upgrade (or downgrade (downgrade enabled from BIOS)) the 1.5.0 the following erroneous or misleading error message is displayed:

• BIOS Updated blocked due to unsupported downgrade
  

Like I said, the current 1.5.0 version does not allow itself to be replaced and give this misleading error message.

I also tried the Linux command:

Code:

fwupdmgr get-updates

But for the Bios I get this error message:

Code:

├─System Firmware:
│ │   Device ID:          86916062c3d836787e2824f9935d5f8cfafb473d
│ │   Summary:            UEFI System Resource Table device (updated via NVRAM)
│ │   Current version:    1.5.0
│ │   Minimum Version:    1.5.0
│ │   Vendor:             Dell (DMI:Dell Inc.)
│ │   Update State:       Failed
│ │   Update Error:       failed to update to 0: error-unsuccessful
│ │   GUID:               1615a963-8806-490d-aaa3-a9ed02c6c6b6
│ │   Device Flags:       • Internal device
│ │                       • Updatable
│ │                       • System requires external power source
│ │                       • Supported on remote server
│ │                       • Needs a reboot after installation
│ │                       • Cryptographic hash verification is available
│ │                       • Device is usable for the duration of the update
│ │   Device Requests:    • Message

Update failed when I tried to continue with fwupdmg (fwupdmgr update).  

I also tried flashrom, the command:

Code:

sudo flashrom -p internal

Leads me to this:

Code:

...
Using clock_gettime for delay loops (clk_id: 1, resolution: 1ns).
No DMI table found.
Found chipset "AMD FP4".
Enabling flash write... Disabling write protection of flash addresses from 0xff122000 to 0xff162fff failed.
Disabling read protection of flash addresses from 0xff130000 to 0xff18dbff failed.
FCH device found but SMBus revision 0x61 does not match known values.
...

Similar issue: #292
I was able to extract the bios.bin from the Dell OptiPlex 5055 System BIOS.
Is there any way on how I can update the firmware from the running computer or CH341A BIOS Flash is my only hope?