AR mk1 - OS versions other than 1.45B or 1.31B

Hi there,

does anyone know where i can get older OS version other than 1.45B or 1.31B?
These are the only ones offered on the support site for the AR mk1. I would like to try to up,- or downgrade to another OS.

My AR mk1, OS.145B freezes upon the start when the pads light up in different colors. I I tried an empty reset, factory rest but it freezes again upon restart. I tried to downgrade to 1.31 B, and also upgrade to 1.46 BETA 1, which both didnt work. I updated via C6 and MIDI. The file was also fully received, but every time I try to start it gets stuck on the startup screen again, this time with the just installed new OS which appears briefly while starting.

The first few times it froze at the end of the startup sequence when all pads light up in different colors. It froze on the last pad with color blue, but now it gets stuck even way earlier.

Factory reset and empty reset from the early startup menu dont work, as it gets stuck again on the startup screen as soon as the AR tries to restart.

Anyone an Idea?