Dell Chromebook 13 (7310) will not boot into recovery mode no matter what I do. Help?

I have a Dell Chromebook 13 (7310, Core i3 model) purchased in 2015.

I am trying to boot into recovery mode by pressing the Esc + Refresh + Power keys, but when I do so, the screen goes black and then restarts normally on the login page. Below are the actions I have taken:

- Removed the WP write protection screw

- Removed the battery

- Removed the SSD (recovery OK but unable to activate developer mode Ctrl + D)

The goal is to install Linux on the PC.

What happened on this computer ? I have seen others with this computer installing Linux without any problems.

I don’t know what else to do, do you have any ideas?

flash the firmware directly using a ch341a USB programmer as per the instructions on my site

Thanks a lot for your reply and your hard work.

Any link to advise me to buy the programmer ?