Thank you very much for the help and suggestions.
I have already tried many times this cycle "ipod recovery--> fresh Rockbox install -->error --->ipod recovery"
Basically , the steps I take are:
-After a fresh recovery of iPod, I run the RockboxBootloaderInstaller_iPodClassic_v1_0.exe
-There, I select the iPod Partition, then, as device "Apple iPod Classic (6th gen) Unknown" , check all the boxes(if I leave bootloader unchecked, it accuses some illegal operation and it crashes) and then click on "install".
-It requires keeping "select+menu" pressed for 12secs. I do it.
-While it shows the message "Restarting iPod, waiting for remount..." later it comes a Windows pop up saying "You need to format the disk in drive E: before you can use it. Do you want to format it?"
at the same time, on Rockbox it shows the message "Action required:
Could not remount the device, try to do it
manually. If the iPod didn't restart, force
a reset by pressing SELECT+MENU buttons
for about 5 seconds. If the problem could
not be solved then click 'Abort' to cancel." And there is only the Abort button as option .
If I do a reset with "select+menu" for 5 secs, Rockbock keep with the same error message and option to Abort, no changes at all. While it pops um another request to format the disk drive.

If I decide to accept and format it, with exFAT and same Volume Lable as before, "Windows was unable to complete the formatting".
I click in Abort, and I see that in "My Computer", the iPod is shown as "USB Drive (E:)" but with no display of capacity (I guess it is because it got unformatted).
After a new reset, it offers to format, this time I accept and it works.
In Rockbox I click to install again and it shows "Could not find mounted iPod".
