Hi, wanted to give an update. I bought a new FE Echoes cartridge. Sadly it was also dead, but this time I managed to fix it. As the proccess has been curious, I wanted to document it here, for anyone having a similar situation.
First I tried the default script of 1.2 ver. (20 refreshes) several times, getting these results:
1st try: 144.000 refreshes.
2nd try: 44.000 refreshes.
3rd try: 15.000 refreshes.
4th try: 8.115 refreshes.
The 5th try gave me an extremely low number of refresh, so I tried to verify the cartridge and succeded!. I booted the game and everything worked perfectly. After that I went to verify it (just to make sure everything was ok), and to my surprise the proccess failed, so I ended up running the fixer again getting 14.000 refreshes.
I then tried the SELECT version (1 time) and the 100 refresh version several times, getting these results:
1st try: 813.000 refreshes.
2nd try: 749.000 refreshes.
3rd try: 770.000 refreshes.
The number of refresh kept increasing again, and when trying the 20 refresh version, there were some chunks stuck (with around 7800 refresh, as similar to my original cartridge) so I was about to quit. But finally, after running one to two more times the 100 rf. version, there where no more stuck chunks. I verified several times, booted up the game and verified again, and now there were 0 issues!!
I don't know the reason why some trys had more refreshes than previous ones, or how it went from having several chunks stuck to 0 in one run of the fixer, but it is what it is, cartridge fixed! so thank you again skawo!!