Elect a PRIMARY when two nodes are unracheable among them

Hi, I’m new with MongoDB and I have a silly question.

I created two VM (mongodb1-test: SECONDARY & mongodb2-test: PRIMARY), in each VM i installed mongo and created a replicaset.
I disconnected from the network my VM mongodb2-test, and the two nodes became SECONDARY.

I tried to set the mongodb1-test as PRIMARY, but i get this error :MongoServerError[NotWritablePrimary]: New config is rejected :: caused by :: replSetReconfig should only be run on a writable PRIMARY. Current state SECONDARY;

I know is needed 3 nodes in a cluster for the election but im trying it with two nodes. I wonder if I can force one secondary to become primary when the connection is lost among the nodes. Or if I should use 3 nodes instead of two.