@yguignot I think the instruction set you are missing is this:
You can just turn off your FP3/FP3+, then press the power button and volume down button at the same time until the device vibrates. After some seconds you’ll see the fastboot mode.
There are longer instructions to get you fully in business, but is this the missing step? 
Thank you aibd
I recently know how to get to the fastboot mode; I can see a black screen with a few lines, one in red reads “device state locked”.
What can I do then? Start from there and unlock the phone? I don’t understand much of what I’m doing, I don’t even know what Fastboot mode is… (I’m 67 and when I was young modern telephones had dials 
)
Yves
While it is true that this will boot the phone into fastboot mode, I’m quite certain it will not help here as the problem already occurs earlier:
At that stage the installer uses adb to determine which phone model is connected.
And that is failing.
I may repeat myself, but it would be really, REALLY helpful to see the log file…
I know you want to help me Angel, but the content of the logfile is cryptic for me; it requires programmer capabilities, not for me; I’m a very basic user (telephone, sms, mails, pictures, etc.)
what I want is to escape Google.
I could get in touch with Piero; he is OK to help me; it will be in my native language and, may be, I’ll feel more at ease to cope with these “flashing” issues.
Thank you for your help
Yves
You don’t need to read and interpret the log file yourself. Just share it to us so we can have a look. 
Sorry Angel I’m really bad at understanding all that;
I thought that the log file was the link you gave me in your message; obviously it isn’t; what is it? is it on the phone or on the computer?
I’m desperate😕
Yves
Please don’t be desperate! Small steps!
Look for the log file on your Linux PC in
~/snap/easy-installer/common
Thank you,
I’ve found it but there are 16 files of various sizes in it. I did so many attempts
Shouldn’t I erase them and restart the easy installer procedure from scratch to have a clear log file?
Yves
All the logs will be independent, so to start again is ok, but why not send two of what you have? Send the biggest and the most recent.
Are you familiar with https://haste.tchncs.de/ ?
You just open the link above, Copy and Paste your file. Save. Collect the new url, of the saved document.
Paste each url into your next post.
Hello Iain,
I had a look at the files and the biggest one is 400 times the same thing; probably because I let the program detecting unsuccessfully the device for a long period. I imagine it is useless to you.
I send you the last but one because the last one seems incomplete.
I hope you can have it through this mail; I don’t see how to send a file via the forum and I’m not familiar with Haste …; if it doesn’t work, I’ll try with that system. Just tell me
Sorry but I’m an old bloke far away from the connected world, but I don’t want to be under the scrutiny of Google, Microsoft, Apple, Amazon & Co
You’re kind to help me
Yves
(Attachment 5dcc4228-deee-4575-85e9-284b49c167e2.log is missing)
Here is the document through Haste …
I hope it works this time
https://haste.tchncs.de/kuxoqukara.php
Leaning by doing…
Yves
Oh, one important thing: the USB cable you are using, have you successfully used it before to transfer files between the FP3 and your computer?
I’m asking because some cables can only be used to charge the phone, and those would be useless here.
Yes, it is fully operational; I already used it to transfer pictures from the phone to the computer.
When I connect it to the computer, I can see all the phone directories from the computer
That’s why I’m surprised at "easy installer’ not detecting it.
Yves
Great, so it is just the same as you said at the start! Easy Installer is not detecting your phone!
I expect you already read the Fairphone instructions for unlocking, they are not easy to read, n’est-ce pas!
I could help you go through those instructions, step by step, (perhaps @piero would be better), otherwise I will step back for a bit, I never had a Fairphone. 
I’ve just made a new attempt and the problem in still the same: stuck at “detecting device”
Attached, the corresponding log file
https://haste.tchncs.de/irabazecum.php
What I don’t understand is when I should unlock the phone: before launching “easy installer” or later on, during the easy installer procedure?
I’m a bit puzzled here. In addition, all my attempts to unlock the phone, according to the procedure from Fairphone, have failed, so far.
Thank you all
Yves
Yves, I think you realise, that is the problem.
[Here is me stepping in again!] Perhaps post a link to the actual Fairphone instructions you are using and try to describe where you fail. 
Well, the installer will unlock the phone during the installation, but the problem is even earlier.
For those interested in the details (from the log file):
The detection is tried via /snap/easy-installer/17/easy-installer-linux-x64/bin/adb/adb devices -l
But the output is always List of devices attached and then an empty list (i.e. no additional output at all).
The problem is: why does the output look like there is no phone connected at all? Possible reasons I can imagine
Now this is a strong hint that the first item is the problem here. As far as I know the phone directories are not visible when USB debugging is properly enabled.
The developer options should look like this (after scrolling down a bit)
I assume it’s called “Débogage USB” or “Débogage Android” in French.
You are right Angel!
the problem was that, when getting to the “uSB debugging” step, my phone screen was different from that in the easy installer; in fact I didn’t activate USB debugging; this time I did and it works.
So I carry on with the installation, fingers crossed!
Thanks
Yves
Dear Friends, I’ve succeeded in installing /e/! (quite easily this time)
But my troubles aren’t over yet!
Half the apps don’t work and I’ve lost all my contacts which were on the Sim card. I thought that the sim card would not be modified by the /e/ installation…
I think the most simple now for me, is to contact Piero for his help; it will be easier in French if there are settings to carry out.
Thank you all
Yves
Great to hear that the installation worked in the end 
