Mate 20 flash fail

[toxpan]

This is about a Mate 20 HMA-L29 (shop-demo).

(1) After flashing it with "Hima-L29C_9.1.0.310(C10E10R2P1)_Firmware_9.0.0_r3_EMUI9 .1.0_05015KXP_FRP_bypass.APP" including adequate preload and cust files using dc phoenix it worked well (with minor shortcomings).

(2) Flashing it with Hima-L29CA_10.1.0.288(C432E8R1P5)_Firmware_EMUI10.1.0_0 5015LAX.APP was a fail. This process might have been interrupted with an error before writing the preloader + the cust.

(3) It still enters Fastboot or Upgrade mode - but not Software Testpoint. But any try to reflash it with another firmware ends with an "Error downloading file" when trying to write Base_verlist partition.

I provided pics of the telephone Info from fastboot (hcu) and the error in dc phoenix.

Any ideas from the comunity to make it work again?

[toxpan]

I managed to enable hardware testpoint - making it possible to change oem info or (probably) to temporarily unlock the bootloader. Any Ideas to get a clean firmware install done?

[Valdemaras]

You should use temp load and unlock bootloader option on dc-phoenix and then attempt to flash it with full stock rom.

[toxpan]

Which method would you suggest to flash it with the full stock rom? Thanks!

[Valdemaras]

Standard one. Flash in update mode or rescue recovery over fastboot

[toxpan]

I'm not sure if i got it right: Are you suggesting to flash it with dc_phoenix or another flash tool?

[Valdemaras]

You should be able to flash it from internal storage or sd card. Otherwise can also use DC-phoenix to attempt it.

[toxpan]

FIashing with any method still ended with numerous update errors. I traced the problem down to a wrong or damaged cust & preloader. I used phoenix to temporarily unlock BL and to flash it with a board image using IDT. After that phone booted well. Restoring oem info to also worked well. After that, flashing with "Hima-L29C_9.1.0.310(C10E10R2P1)_Firmware_9.0.0_r3_EMUI9 .1.0_05015KXP_FRP_bypass.APP" resulted in an almost perfectly working phone. But repairing the IMEIs (with cert files) ends in "Missing signature files! Repair signed files skipped." How could this (final) issue be solved?

[Valdemaras]

You need to flash then NV partition backup. On DC-phoenix there is the button "Download file" - press it. page opens, enter in its search field "NV" and look for partition backup with your phone's CPU, flash it, then repair the device's IMEI, this will fix the "missing signature files.." problem.

[toxpan]

Thanks a lot! This sound good! Unfortunately with the first number flash trials i just got it to boot to eRecovery. There are three different versions of NV partitions for Kirin980 (*v1_L04, *v2_L29, *v3). What is the difference and which one suits the Mate20 (HMA-L29 --> probably the v2_L29, but there are a bunch of different phones with L29 in their name). Is there any recommended flashing order? Such as (1) flash board firmware, (2) NV partition, (3) restore OEM data + Imei, (4) flash stock rom.

[Valdemaras]

NV partitions flash will solve your IMEI repair problem. You should use one close to your phone version if it's L29, use L29 backup of your CPU if there is such. You can flash NV partitions after full stock ROM.

[toxpan]

Flashing the NV partion did not solve the problem. Instead, the phone booted *almost* correctly but constantly crashed while playing the startup tune or a continuous bootloop. This behavior did not change using different NV partitions for the CPU. After reflashing it (with temporarily unlocked BL) with the board image (the one that worked before) the phone interupts booting and enters fastboot mode. I can still enter update mode, hardware testpoint und eRecovery. Any advice?

[Valdemaras]

It solves that problem 100% for everyone else, you may consider your phone with damaged emmc then if nothing helps you. Now can only again flash board software from testpoint and revice as you did earlier. Nothing new in that.

[toxpan]

Is there a way to delete values e.g. Bluetooth MAC in HCU with fastboot/xloader connection? That is, to empty it rather than to change it to another value?

[Valdemaras]

No, there isn't, maybe only by flashing board software possible to remove them.