Can't connect charge cable to Eufy doorbell.

I am usually pretty good at figuring things out but I can’t figure out how to insert the charge cable into the Eufy doorbell. I see what looks like a male micro USB piece at the bottom of the doorbell but can’t figure out how to attach the cable to it… The piece moves in on the doorbell but not enough to grasp the cable.
What am I missing.
TIA
f1jim