How can I re-flash stock firmware for my Nokia 6.1? I've developed an issue since the last Android 10 OS update where the phone doesn't charge unless it's in 'USB Controlled by device' mode, which it usually fails to switch to. I'd like to try flashing stock firmware to it, as resetting to factory default didn't fix the issue.
I've tried downloading a stock firmware file and using the recovery mode option to install from SD card, but alas the timestamp on the file was older than the current OS, and so it refused to downgrade.
Since I'm a complete newbie to the android hacking world, I'm looking for an easy to understand solution to install a fresh stock firmware / ROM (not sure what the nomenclature difference is) or failing that, backing up the existing firmware and re-installing that. Naturally, the phone isn't rooted nor is the bootloader unlocked etc, nor do I currently know how to do those things.
Any assistance would be much appreciated.
Warning: Before flashing, always make sure that you have the correct tools, ROMs, etc. because you can brick your phone if things don't go as expected.
I found at least 2 threads from xda-developers. Before you start, your bootloader must be unlocked.
From the first thread:


Install the OST tool.
Replace the EXE file in the program files with the patch file you downloaded.
Delete the Onlineupdatetoolexe.config file. If you don't do this, the program will not start correctly.
Put phone into download mode ( either by powering it off, pluging into USB cable and immediately hold power and volume down. Or if you can boot into android with ADB debugging, just do a adb reboot bootloader.
Pick firmware file and click next.


From the second thread:


Download Nokia-SDM660-Tool.zip &amp; Copy Nokia-Tool.exe
Download latest HOME BREW Stock Rom And extract in one Folder and name it as STOCK ROM
Now add Nokia-Tool.exe in to that respective STOCK ROM Folder
Now connect phone to pc
Go to download mode
Now Open Nokia-Tool.exe
Now select Button according to your Phone code
Example Iam Using Nokia 6.1 Plus &amp; My phone code DRG &amp; so i will choose [ DRG B2N CTL PL2 ] same option for 6.1 , 7.1 &amp; 7+ but for 7.2 &amp; 6.2 users choose [DDV SLD]
i will click on [ DRG B2N CTL PL2} According to my phone as i explained in point no.8
wait for 10 min Tool will flash the rom &amp; your phone reboots to system.
So finally this is what the exact standard method to flash stock rom on Your devices


Important: Read the linked threads (and others). If there are steps that you don't understand, ask the authors questions so they can guide you throough the process.
Nokia 6.1 (2018) ROMs, Kernels, Recoveries, &amp; Other Development