Problems to upgrade after an infection

A couple of days ago i have some issues with a router rb3011, i have found some firewall rules created and some messages aparently due to a system access from some type off botnet because the mikronit was not with the firmaware up to date, i have changed all my passwords and due to one suggestion in Mikrotik forum, I have tryed to upgrade the firmware several ways with no success, I am not a mikrotik expert so i need your advice to see if there is a way to uograde the mikrotik device, there was a second rb3011 infected and i am having the same experience, the ones that are not infected are upgrading ok.

Thank you in advance.

Google for “mikrotik netinstall”. If you’ve never done it before, expect that it may not work at the first try.

https://wiki.mikrotik.com/wiki/Manual:Netinstall