First of all, my Cool-er is EB-600EM based. How do I know? because PB has a settings-> about device, that reports this information.
I did all the points as stated in the first post from Qxr. Read it thoroughly you must certainly be ready to get your cooler bricked.
I did have a first attempt which failed with a FAT formated SD. I saw all of the first "dots" but nothing else happened. With the same SD I tried to reinstall Cool-er firmware (which I had to google for, because Interead cooler's site has dissapeared).
My "semi-breaked" device showed only three of the dots when swiched on, and when "power on + third button + reset" with that sd showed all of the dots (I haven't counted if there are five or seven) but nothing more. (I couldn't install neither FR TO PB, nor COOL-ER firmware... it was late at night and I didn't try anything else).
After changing the SD with another one which was FAT32 formated, I tried anew FR TO PB (following the steps of the first post) and it succeeded. My device has 1Gb internal memory, so I did have to do the editing which was quite easy (as I said, follow the steps).
When things went wrong, I saw the six dots and nothing more for ten minutes. When things went OK, I saw the six dots, and ten seconds later a screen in russian with five or six check-boxes which were checked one by one along the time the procedure ran.
Once finished I found a rswitched on ussian PB device, which was easy to convert into english (the pertinent options are in both english and russian).
Once in english I upgraded to 15.3 following the instructions for PB 301+ on http://pocketbook-usa.com/support/pocketbook-301/
Here it is, with the latest PB version and in english.
Why did I change? Because Cool-er got frozen with certain pdf files, and didn't allow me to delete them (I had to remember those files, connect to a PC, and delete them from there). And of course for the fun of doing it.
Hope this helps anybody.
Excuse me if I have not introduced myself I was just willing to help because I read a post saying there were no success stories (and I, myself thought I was mad for following instructions found on the internet without success stories behind them).
Anyhow you know you're taking a risk if you try the instructions.