Good morning,
I have a problem with the MikroTik CRS354-48G-4S + 2Q +.
The situation is so missing that I decided to write here.
Firmware 6.48.1 (stable) is installed.
The problem with him appeared about two months ago - assuming the user, after a few minutes / hours his account was deleted (all settings were left and the switch was not reset).
This week I decided to update to 6.47.10 (long term) and broke down.
When trying to update, I was thrown to the settings from 2 months ago and the version was 6.48.1 ...
I had a backup from exactly this device, but it won't restore - it says it's incorrect. Cool...
So I recreated config (miraculously because I didn't have the configuration export), but I still want to update!
I found that I will try to do it again - unfortunately, each time the switch resets, and after the console I see a message about insufficient space, and the firmware remains on 6.48.1.
Interestingly, 16Mb / 16Mb is still busy, although there is nothing there ...
So I wanted to remove unnecessary packages (eg LCD, GPS), but it is also impossible - they add to the queue, but after the reset are still installed (also the message about insufficient space).
In addition, there is a wireless package which when clicking Check Installation will reveal the message "damaged wireless @ package" ...
The Downgrade and Reset configuration options do not help - the router clears the configuration, but is still on the same firmware version ...
Currently, with each restart, my configuration returns to the one in which there is only an IP address and the possibility of logging in (no interface names and vlanes were given) ...
I like MikroTik, but what happens to my switch is a joke.
How do I upgrade / downgrade now? And what chance do I have that it won't become a useless brick?
I am using the stable version - so it can also be unstable ?!

I suggest you to perform full netinstall. This procedure formats flash storage and removes all configuration.

As you're mentioning multiple IP addresses it seems like you're using the device as router. There are multiple problems with such usage:

1. CRS3xx devices are primarily switches. While they can perform L3 operations (such as routing), their performance is low due to slow CPU
2. by default they come without any firewall settings. If such device is exposed to "unfriendy" networks (e.g. internet), it will be hacked very quickly
3. etc.

So if you can, get a proper router for routing, even some cheap Mikrotik devices can be better routers than CRS3xx devices.