Have you checked the voltage at the doorbell? Should be in the range of 16-24 vac. Also check your doorbell transformer rating. Should be printed on the side of the transformer. Many standard doorbells only came with enough capacity to feed a chime from a pushbutton. The video doorbell needs enough to ring the internal chime, record video, and send a signal. Eufy specs for the transformer are 16-24 vac and 30VA.
Another thing to check is for an external fuse on the transformer. You may have blown it when wiring the doorbell.
If it’s an Eufy Wired doorbell then it doesn’t have a battery. Unless you mean you have a wireless doorbell that you just happen to connect to your transformer to keep the battery charged, in which case use a multimeter to verify voltage at the doorbell.