When you have done that, don't forget to do a firmware upgrade again from the Linksys firmware using the Linksys firmware, so both partitions are overwritten and contain a stock (and identical) firmware.
Otherwise in the future if this device fails to boot for some reason it will reboot into the OpenWrt partition and that will be an issue for your friend.
For the benefit of other readers, where is the download link for your distro?
l was about to ask the same as i've been going around in circles at Google trying to find the Bin file. 
@bobafetthotmail thanks for the reminder about doing both partitions...
I'm sorry...
But they asked me to remove the links and the files of my distro and my commits, and they celebrated the moment I did it (even tho, that device have official support thanks to escalion and me).
Therefore I'm not uploading the binary files anymore, and never will upload or share my work here. Contact me in some random social network if you are really interested.
@NoTengoBattery in Twitter
notengobattery@gmail.com for emails
GitHub/NoTengoBattery
P.S. This will be mi last post in the thread. I've already muted this.
Could you give a link to Github so everyone can go to the same place and help each other as i'm sure plenty of people in a situation like me will appreciate your work. 
If people email you or go on social media then the help will get scattered and confusing.
Thanks
I've dropped a PM and email to you.
@bill888 Can you PM me when you find out the details.
I found openwrt at his Github page but i can't see any bin file to download or any way we can start a issue thread for helping each other in a single place.
thanks.
Does anyone know if the standard Linksys TFTP procedure works using their stock Firmware to reflash?
https://www.linksys.com/us/support-article?articleNum=137928
Theoretically it should, as TFTP is the file transfer protocol used by the bootloader.
By looking at the device's bootloader configuration dump in the wiki (the u-boot envs) https://openwrt.org/toh/linksys/linksys_ea6350_v3#Notes
It does seem to have tftp support, as it has "serverip" and "ipaddr" and has the two lines "flashimg" that load the image from tftp and flash it on the device.
It seems the device has IP 192.168.1.1 and will expect the server to be at 192.168.1.100. It also expects the image to be called "civic.img" (civic is the board name of this device, it's not random)
I just don't know how to trigger that. Maybe that application you found does it.
If it does work, please add the tftp recovery instructions in the wiki.
If he does not provide binaries to you through email or whatever means he said, free of charge, I can compile from source using his github project.
Thanks Bob
That TFTP.exe on the linksys page looks archaic so i'll have to dig out my old WinXP laptop to see if it will work , I'm not going to risk Linux Wine in case it craps out and crashes.
"Unable to get responses from server"
I had a quick go and got the above message , i'll try again later when i have more time and i will check that i can ping 192.168.1.1 / 192.168.1.100
I give up with TFTP as i've just spent the last couple of hours trying every guide i can find and nothing works...
Modern Linksys models are supposed to have a fail safe that they will capture a TFTP image at boot but i don't know how your supposed to send a image when the router drops the lan sockets at statup for both a hard and soft reboot , I followed the guide in setting a fixed lan address for a fast connection but it still doesn't work.
I hope @bill888 can get somewhere with @NoTengoBattery otherwise i will have to buy a new router for my friend as obviously i'm responsible for talking him into using openwrt. 
Can you not swap your unit with his if you haven't done 2 upgrades?
Looking at the scripts, it shouldn't take much to reverse engineer the upgrade bash script to work on standard openwrt.
I ordered the routers and done them both exactly the same , that's why in another thread i needed Mac override to work so i could swap between routers and get the same internet connection to test they where working ok.
Perhaps may have to go forward with @bobafetthotmail earlier offer to compile a binary from NoTengoBattery's github project ?
Update: I have to apologise to @NoTengoBattery for suggesting earlier today I had not heard from him. It transpires I did receive a very detailed email which includes the sysupgrade image with full instructions, which I have yet to digest. The email took almost 12 hours for it to be delivered and finally appear in my email inbox.
Have you tried connecting a switch (a basic unmanaged Ethernet switch) between the router and the PC? This way the PC doesn't lose Ethernet carrier while the router reboots, so the port stays active and configured with the proper IP.
I personally don't feel like wasting my own time to figure out what that script does, what it needs and how to replicate that in OpenWrt (assuming it can be done without enabling different compile options, and at that point I would need to recompile a firmware anyway).
I have a build environment already set up as I compile OpenWrt for my own devices anyway.
git cloning and launching a build takes a few seconds of attention and very little brain power, all the leg work is done by a machine.
So perhaps may have to go forward with @bobafetthotmail earlier offer to compile a binary from NoTengoBattery's github project ?
Here it is
DISCLAIMER: I have not tested this in any way as I don't have the device, I didn't even look at the script so I don't know how to use it. USE IT AT YOUR OWN RISK
Once you or someone else confirms that this works, I'm uploading these images in the wiki (Openwrt.org site) so it can be used as part of a permanent "return to stock" procedure in the device page.
Would be appreciated if you or someone else writes down the steps and the commands he used to go back to stock, even just here on this forum. I can copy them over to the wiki.
Please don't. The wiki is not the place to share big files like firmware images.
Can you upload the images to a google drive or thelike?
It's a recovery image that will be used only for going back to stock firmware. Bandwidth utilization is going to be minimal since I doubt many people will need this at any time.
I don't think space is an issue either (I'm probably going to load only the sysupgrade image though, so it's going to be 6-ish MB, not 30MB).
Using an external site is bad for the same reason OpenWrt developers don't allow people to put links to docs and files in the commit messages. External links will go dead, you can't rely on them.
Besides, I'm not going to be maintaining a secondary account on Drive/Dropbox/whatever for a couple files that can be placed on the wiki server, that's silly imho.
If we start to get a lot of them in the wiki and the drive is filling up (I doubt it) or you see that they somehow attract too much traffic for the server (I also doubt it), then it can make sense to migrate them outside.