@Phelixdegreat, after uninstalling it, try...

List the packages that have been installed but still have config bits left:
dpkg -l | grep "rc "

If there's anything listed, purge the packages, whose lines start with "rc":
sudo dpkg --purge <package-names-as-listed>
- you can do them all at once, if there's more than one.

Now reboot the device, even if you didn't need to do any package purging.

You want to clear all Opera bits from your system. so when you're back up and running, look for anything where Opera might have stored config files, cookies etc.
find / -iname opera 2>/dev/null.
remove the opera directories:
rm -r <directory>.
Hopefully, you won't need to be logged in as superuser to remove these bits.

Reboot. Possibly, you don't need to here, but it resets things.

Now try reinstalling Opera.