I couldn't update a rooted B132 to B510 because of some modified file used for a MD5 check by the installer.
These files were the /cust/channel/weurope/cust/local.prop file(*) which was manually modified by me and /etc/audo_effects.conf which was modified by Viper4Android.
Restoring them to the original was easy, I've just added a pair of # to the first file and v4a just add a section to the second, but making a backup copy of configuration files before changing them is always a good idea. After that upgrading was smooth, except for the root app which had not been removed and that it was not possible to remove because considered a system file. Reverting to B111 and then back to B132 and B510 solved the problem.
(*) channel may obviously change in other countries