We did the firmware upgrade of a RB600 from version 3.30 to 4.11. We went back to 3.30 and upgraded again to 4.11, but now we can no longer access to the RB. The RB starts and hangs at the login screen. After a few seconds it reboot.
I thought about upgrading the RB through Netinstall, however, it was in a tower and received electrical surge on LAN ports, burning two of them (ether2 and PoE). But it worked fine before the upgrade even with only one LAN.
What can I do to save this RB?
Is there way to send RouterOS through the serial port?
And if we use a CF with linux to copy the package for RouterOS Nand RB?