Diagnosis
The rechargeable battery inside the parent unit is worn out. This is common after a year or two of daily charging cycles. It's a lithium-ion pack that loses capacity over time.
How to Fix It
The official fix is a battery replacement. VTech sells a replacement battery kit (model BRM5764) designed for this unit. To install it: 1) Power off the parent unit. 2) Remove the two small screws on the back that secure the battery cover. 3) Gently unplug the old battery's connector from the main board. 4) Plug in the new battery, tuck it in, and replace the cover and screws. Charge it fully before first use.
If That Didn't Work
If a new battery still drains fast, the issue might be software. A constant 'Searching for Camera' loop is a huge power drain. Make sure the camera is powered and paired properly (see the first fix about re-syncing). Also, lower the screen brightness in the settings menu.
Heads Up
When ordering a replacement battery, get the exact VTech model. A generic battery with the same voltage might fit, but it could lack the proper thermal protection or charge controller, which is a safety risk.