Yesterday I wanted to upgrade from an unstable build( I think it was 3.6) of rockbox to version 3.7.1. I have a Sansa clip v1. I removed the .rockbox folder and replaced it with the new .rockbox folder of build 3.7.1. Since then Rockbox is giving 'bad checksum' on startup and autocloses the player. I can only boot up by plugging in the USB or pressing left button+power to original sandisk firmware. I tried to upgrade firmware, but the player doesn't detect m300a.bin while it's on the root of memory, so I cannot upgrade the firmware. Rockbox utility can't remove the bootloader. Manually uninstalling doesn't help. I also tried to formatting the player with no luck( it says file not found, copying the .rockbox folder gives bad checksum). I also tried to replace the checksum with a hex editor with the checksum displayed on the second line of the display but it doesn't works. New installation through rockbox utilty also doesn't work despite the message 'installation succesfull'. Please help. What can I do to install rockbox 3.7.1??