[Huawei P20 Lite Questions & Answers] fbh59:
One way is to try to recover your device using E-Recovery and download the ROM within E-Recovery itself(it will be autoflashed). But e-recovery might fail to download the ROM if your kernel has been changed. In my case, it has failed even though kernel was default kernel. E-Recovery might fail to download if you completely wiped out all partitions. If you completely wiped out all partitions you will find hard time to get back 1 particular partition back i.e. HiSuite package Partition(though you can download from internet), unless you have taken a full nandroid backup or just backup of that partition using twrp.

Now if the above method doesn't work,

The other way to recover is to first download the dload version of the ROM(the links have been provided in another post belonging to P20 lite thread). Instead of 3 files(used in Hurupdated method from Firmware Finder site and app), these links will give you just 2 files. Open them and just extract the *.APP files only. Rename both the files into UPDATE.APP. APP should be in capital letters only if not, just make it in uppercase by yourself. The update.zip will give you some UPDATE.APP which will be around 4 GB and the other one around 1-1.2 GB. The only method by which this will work is to use external SD card. Now if the UPDATE.APP is more than 4 GB then format the ext sd card in NTFS or ex-FAT format. If you dont have sd card adapter then use "AParted" app from play store to do the job. Now copy the first APP file. Keep pressing power and vol up and down buttons together(after switching off your device) till you get the bootloader unlocked warning screen. Now your phone will automatically flash the file and reboot. The process might take around 5-10 mins.

After flashing, your phone will boot successfully. In some cases after flashing, you will get a warning that some serious problems have occurred(but after a successful flashing). It will ask you to completely wipe the device. Just wipe it and then it will reboot just like a new phone asking you to sign for gmail details etc etc(you can skip them if you want). But still flashing is not complete. Now you need to repeat the process with the smaller APP file(after renaming it to UPDATE.APP), but now no need to wipe the device.

Voila!! Your phone is in a working condition now. But bootloader will be locked again. But you can unlock it again by enabling OEM unlock settings and then under fastboot(which again will factory reset your device) and use Magisk for your enjoyment.

In case you are not getting the dload version of the ROM of the desired variant( i.e. C432 or C675 or whichever you want), there is one paid site to get that. Google "easy-firmware" for that. Huawei P20 lite dload ROMs are available in that site. You might have to pay 15 $ for 40 GB downloads from that site. In case you dont want to pay, then you just need extra high speed data because you have to download a lot of files. So if your ROM is not available for download and you have to use a different variant ROM then after flashing with the different variant ROM and unlocking the bootloader, use HwOTA to rebrand your phone to the correct variant and then use Hurupdate to flash the final ROM(this time you have to download the 3 zip files from Firmware Finder and rename according to the tutorial).

I hope this helps you out from the doldrums