Correct me if I am wrong, but mint 17.3 is based on ubuntu 14.04 and for that reason opera 51+ should not even install due to a missing dependency, as discussed here
https://forums.opera.com/topic/24994/can-t-install-opera-51-on-ubuntu-14-04-lts/
However, if there is a corrupt profile that prevents it from starting, with opera not running, backup your ~/.config/opera folder first, then delete it, and then launch opera again, forcing it to make a new profile folder. If it does launch, then it is a profile problem. If it does not launch, well, you should look elsewhere.