Rt6/rneg2 problem with soft

[Tr0liK]

Hello,
I have Citroën C4 Grand Picasso 2011 with a Rt6/rneg2 radio. Few weeks ago my SD card died :C unfortunately I wasn't able to clone card because it has caused some serious crashes with my PC when inserted. So I've started reading how to install new SD card from various sources, and then after buying new 8 GB SD card I've downloaded soft from a polish file sharing site (quite trustworthy). I've tried a few different versions of the soft, but the radio didn't even try to boot when a pendrive with 2.21 or 2,37 was inserted. The only working version that was successfully installed was 2.86B, but unfortunately at that point I wasn't aware of being forced to go to the Citroën saloon to get configuration. After changing language from Czechs to Polish with mirascript, I've found out that my speakers are not working, no matter if I'm using radio, bluetooth, CD or pendrive. So I've decided to format my SD card and try again to install an older version of the software that will work just fine. Then during the process of checking CRC I've got an info that flash drive is bad or sth (seeing Peugeot logo, and background from 2.86B version). Now you know my situation, I shall ask the proper questions. Does the radio have another source of memory that sustains the software even if I remove the SD card? If so, how to remove it completely, so I can install the version I like. And final one - do you have any 100% working files of soft - 2.60 or sth like that, just so I can use bluetooth, navigation and radio.
Thanks

[GiveMeABreak]

You CANNOT downgrade firmware - end of. The firmware not only updates the configuration data on the MicroSD card, but it also writes data to the unit itself.

As discussed elsewhere, if you don't have a backup of your user configuration from Mirascripts, the risk is that you will lose configuration which requires reconfiguring in dealer-connected mode. This should restore all the optional equipment and the correct settings to the BSI.