Hey joaoabs, which OEM version did you download? I have tried that but I get the error message you were originally getting. When I went to the link I saw version FW_EA8500_188.8.131.52978_prod, downloaded that one, but when running it, the error about not being compatible keeps popping up.
Did you do anything before trying to reinstall the OEM on top of the Latest firmware version? I also have 184.108.40.206832 currently running on the Router.
I had the version 220.127.116.11832 and downloaded this one. It didn't seem to care (after all, a downgrade should be a valid use case, I believe). Anyway, I flashed it twice and managed to reach version 18.104.22.16897. In this version, it accepted the latest OpenWRT firmware. Are you sure you are using the factory binary (not the upgrade?).
If it doesn't work, do one reboot and try again. It seems this device has some dual bank and may boot alternatively (not sure how it works exactly).
THats the version that I have tried several times. My router came from US, it could be that the firmware from there is not letting me do the downgrade. Lucky you, that didnt have to go through so much trouble hehe.
Unfortunately I got the router yesterday so I dont have a dongle cable for the TFTP process. Also, my router after I opened it does not have the serial pins. So, from what I have found I have to solder cables to connect to the dongle. Do you know what cables I should use to solder? Is there anything special besides the dongle (which I already order)?
I don't know the specific case for this EA8500, but I've done it several times in the past with other routers.
I usually solder "pin headers" and then use a "USB 2.0 to TTL UART Module" with "jumper cables" to have a serial connection to the router. (If you don't know what these are, you can search these terms in ebay).
Well, will give it a shot when the cable arrives. I did try rebooting the router several times but no luck. I guess I am in the same position as many others. Unfortunately there is a signature code added to the latest version of the EA8500 that does not allow firmware downgrades pass certain versions (to prevent exploits like installing third party firmware).
Will update once I get the cable and play around soldering the to the none existent serial port haha. Thanks for your response.