Can I ask this question which I can't find answers on the forum:
I am selling my Q5 Pro (I still have and use a Q10 Pro 6GB, so the Q5 is surplus now), and would like to remove my personal info from it before sale, but keeping the custom firmware I have painstakingly installed!
It is running Android 7, Custom firmware HMD 2.1.4 2019-06-04.100340, I can't remember why 2.1.7 is not installed, think it wouldn't install or something.
Would a factory reset take it all back to Android 5 and basic firmware, or could I do that reset and it would remove my info?
Thanks for any help.

Still no luck updating to 2.1.7 on my Q5 Pro, but my Q10 Pro took the update no problems, now on PCRistis CFW 2.1.7 on the Q10.
What am I doing wrong on the Q5? I was on CFW 2.1.4, went to OFW 2.1.4, tried to go to OFW 2.1.6 - nothing, tried to go to OFW 2.1.7 - nothing, now back on CFW 2.1.4, the only clue I have is that in the very first seconds of initial boot to CFW 2.1.4 I see a red backgrond and oddly coloured HIMEDIA logo, which then disappears and a few seconds later the correct looking HIMEDIA logo appears, is this a sign that I have an Android problem or some other software problem. Maybe I should go back to 2.1.1 and then up from there? Help please.

On my Q5 Pro tried the update to 2.1.6 paper clip method, just got Himedia logo then nothing but a blank screen for 10 minutes, so have gone back to 2.1.4, any idea why it didn't work? and is it worth it?

WooHoo, I finally did it! Got to Official Firmware 2.1.1

I contacted Himedia, and they could only point me to 2 files, the first to update Android 5 to Android 7 with firmware 2.0.4, the to update to firmware 2.1.1. So I decided to try it, which meant I downgraded to Android 5 first, all OK in firmware 1.0.8
I used the first file, to go from Android 5 to Android 7 with firmware 2.0.4 but I seemingly had no luck, the robot progress bar only got to 80% then the Q5 rebooted, but I was left with a blank TV screen, and just 'boot' on the LCD screen of the Q5, no home screen at all, so no luck I thought.
Remembering all my previous attempts I realised that at this point before if I tried to install an Andoid 7 based firmware, 2.0.1 I did get the Android 7 rings when using the paper clip method, so I knew Adroid 7 was on the Q5, and working. So I upgraded to firmware 2.1.1 paper clip method, but not had a working Q5 since Android 5, and I waited, and then, hey presto - Android 7 and firmware 2.1.1 all good to go, with the official home screen, and old version of Kodi, but it is working.
I will take a deep breath and upgrade to Custom Firmware 2.1.1 and then, another even deeper breath, and try to go gor 2.1.2
Such a long journey, the scenic route, but I appear to be where I want.
Thanks to all.

I am sure I did try the android 5 to android 7 with f/w 2.0.4 before, and it didn't work, but, as I can't be sure having tried so many things so many times, I will give it a go! Hopefully, if it fails, I will just get myself back to custom 2.0.1 fromAndroid 5 or wherever else the Q5 lands up, telling if I have 5 or 7 by whether I have a robot or a ring.
I will be using a different usb port this time, just to see if that makes a difference, and maybe fat32 usb and ntfs usb.
Will try Himedia just in case they can help.

No, the progress bar rarely goes to 100%, except, if I remember, when upgrading Android 5 to 7, which I have done at least twice now. I downgraded and then went back in steps as advised by pcristi, but neither of his 2 ways of getting to 2.0.3 worked.
I am very computer literate, so all my hidden files and extensions are always on, and the correct .zip file is always used.
When I re install custom or official 2.0.1 the progress bar only gets to 70 - 75% but the system then boots and runs normally. It is only when trying to go to 2.0.3 that I get the problems.
Do I definitely have a UK version Q5? I think so, as I have 5GHz wifi available (though not used) and 8GB memory, and, I assume, it would not run 2.0.1 when installed.
Is Android 7 fully installed? Can't answer that for sure, maybe there are diagnostics available to understand where the incompatibility lies, or what is blocking the 2.0.3 install. I am even using NTFS formatted usb drives as told by pcristi, but fat32 drives result in the same behaviour.
All my normal end to end fault finding analysis are not finding the problem, can't think it is hardware, so O/S problem seems likely.
If all else fails, I wonder what, if anything, I am missing by not being on custom firmware 2.1.1, which would be the ultimate aim?

Still no luck whatsoever! Tried all the suggestions (Thanks pcristi) but nothing gets me beyond Android 7 custom firmware 2.0.1. Stuck there, so I have updated all the apps I use to the latest, incl. Kodi 18.2, and will carry on as it is.
Still no output from the composite phono connection, but I do now have a small unit that takes the hdmi out of the Q5 and gives composite and stereo to 3 phonos, and that works, as well as composite can.
Wondering if I should try the shorting out the pins on the motherboard trick, or am I likely to brick it?