Hello,

Netinstall and normal upgrade from winbox (system packages/check/download and install) will brick the router when used 6.34.3-2-etc, The router will not boot until powered on with reset button pressed 'till all interface's leds are off and then releasing the reset button, it will boot. Every system reboot will put this router in brick state, no matter what firmware is used, 6.17, 6.24, etc.
Even with the latest RC will act the same, after reboot, not booting anymore untill the reset procedure is applied.

Do not update software if you work remotely.

Forgot to mention, not even power cycle will make the router boot.