Play Store not working on Lenovo K3 Note?

I bought it off of Gearbest. Turns out they put their ROM on top of Lenovo's.
When I was prompted to update the software, I accepted, not knowing it plans to topple Gearbest's ROM. It appears it didn't do it well, and ****** up the compatibility, so I keep getting "Google Play stopped working".
I snooped around the internet for a solution (delete data, cache, restore to factory settings etc), and none of which worked. I even tried to uninstall all Play updates, but the phone uninstalled Play as a whole.
I reinstalled via multiple apks, and none of which allowed me to open Play Store. It would crash upon opening. Heard if I flash a new ROM, it'd be fine. Tried that. Couldn't flash it "because phone wasn't rooted". So I tried to root it. Nope.
Tried to download a workaround, to avoid Play Store. Couldn't install any of them either… Help.