Upgrading old RB to 6.48.5 makes cards boot-loop

Hardware MikroTik hardware general
2

Try to first netinstall 6.48.4 or 6.47.10 and update routerboot to this version before installing newer ROS.
For reference:
http://forum.mikrotik.com/t/v6-48-5-long-term-is-released/152469/1