Recently attended a webinar with an ISP who ran through some upgrading methods. Our microtiks were on 6.4.7 Stable . Instructed to upgrade to 7.8 as they were fairly outdated from being shipped but sadly cannot get past loading screen when entering 192.168.88.1
winbox supports layer2, so you can always try the MAC address of the unit.
If you plug your laptop directly into a LAN ports (e.g. typically NOT ether1), wait 10 seconds, it might show up in winbox’s discovery window & from there you can double-click the MAC address (if it shows up) to connect. May save the trouble of netinstall if that works.
Once in you can then do a /system/reset-configuration save-users=yes to get the 7.8 defaults if needed. Or see what’s wrong in the config it got and/or error messages in logs.