Sansa Sandisk c200 v1 - "R/W Mode"

[windlefin]

Hi - Trying to install Rockbox on my Sansa Sandisk c200 v1. I'm using Linux Mint, which I am still very new to. When I try to install via Rockbox utility I get an error message that says: "Could not open Sansa in R/W Mode"

I've tried clicking around on the device in MSC mode - the only thing that shows up is a  "VERSION.TXT" file with a lock symbol on it containing the following:
Base Code: 06.10-S301-06.10-S301.01.05PRT
ODM Ver.: S301-06.10-S301.01.05PRT
OEM Ver.: S301.01.05PRT
Build Type: RT
Build Date: 2007.04.16
Build Number: (Build 13.26)\00\00\00\00\00\00\00\00\00\00\00 (this part goes on endlessly)

I am not sure if this is an issue with Rockbox, or something to do with the MP3 player. FYI - It has the 01.01.05 firmware which removed the option to go into MCS mode unless it is preformed manually.

Not sure how to fix this - any advice? Thank you