Huawei P Smart FIG-LX1 how downgrade android 9

I want to downgrade the firmware FIG-LX1 9.1.0.115 (C10E5R1P4)
need help guys
Flashing firmware FIG-L31 8.0.0.122 (C10)
After flashing through the fastboot I am flashing through the flash card.
Phone writes "software incompatibility with current version "

[SPOILER="full log"]
SigmaKey v.2.33.02
795109527 Sigma dongle 2.33, Initializing...OK
Pack 1: Activated
Pack 2: Activated
Pack 3: Activated
--------- 2019-07-16 11:46:36 ---------
SigmaKey 2.33.02 HiSi: Remove FRP / Huawei ID
HUAWEI USB COM 1.0 (COM41), Provider: HUAWEI Incorporated, Driver ver.: 2.0.6.725, Date: 10.08.2014, USB\VID_12D1&PID_3609&REV_0100
HiSilicon: Kirin 65x
Phone model: FIG-LX1
Version: :FIG-LX1 9.1.0.115(C10E5R1P4)
Removing FRP lock...Done
--------- 2019-07-16 11:56:20 ---------
SigmaKey 2.33.02 HiSi: Enable downgrade
Connecting...Reboot phone and try again
--------- 2019-07-16 11:56:59 ---------
SigmaKey 2.33.02 HiSi: Write firmware
HUAWEI USB COM 1.0 (COM41), Provider: HUAWEI Incorporated, Driver ver.: 2.0.6.725, Date: 10.08.2014, USB\VID_12D1&PID_3609&REV_0100
Firmware file does not match the phone
--------- 2019-07-16 11:58:55 ---------
SigmaKey 2.33.02 HiSi: Write firmware
(ADB) Writing flash...UPDATE.APP
Firmware: FIG-LX1_Global_C999
This operation may brick the phone! Are you sure you want to proceed? [YES]
Phone model: FIG-LX1
Version: :FIG-LX1 9.1.0.115(C10E5R1P4)
Writing flash fw_lpm3...OK
Writing flash fastboot...OK
Writing flash modemnvm_update...OK
Writing flash teeos...OK
Writing flash trustfirmware...OK
Writing flash sensorhub...OK
Writing flash fw_hifi...OK
Writing flash kernel...OK
Writing flash ramdisk...OK
Writing flash recovery_vendor...OK
Writing flash recovery_vbmeta...OK
Writing flash dts...OK
Writing flash modem_fw...OK
Writing flash vbmeta...OK
Writing flash odm.0...OK
Writing flash cache.0...OK
Writing flash system.0...OK
Writing flash system.1...OK
Writing flash system.2...OK
Writing flash system.3...OK
Writing flash system.4...OK
Writing flash system.5...OK
Writing flash cust.0...OK
Writing flash vendor.0...OK
Writing flash vendor.1...OK
Writing flash version.0...OK
Writing flash product.0...OK
Writing flash userdata.0...OK
Writing flash...Done
Restarting phone...OK
[/SPOILER]