while i personally would not buy a refurbished monitor (as i prefer new) it can be a good way of getting a better grade monitor for cheaper. often i recommend looking into it if someone wants a high quality monitor such as ips but doesnt have the budget.
open box suggests a return. i would wonder why it was returned.
honestly its a gamble. check the return policy. if they allow returns for a defective product then you would be stuck with shipping both ways if its a dud. if it works good however you could save a bunch of money.
depends on whether you want to take a chance or not.