A unit cannot be unlocked: there is something wrong with this extension, usually the unlock key is not good.
All extensions are not unlocked: the main problem is that the host, such as the capacitor on the host, falls off.
It is also possible that the lock itself is not good, and it can be detected that the coil inside the lock is not connected.
If you want to change the video intercom, you can consider Anbentianxia. An Ben Tian Xia building intercom is an embedded one-stop operation management. Developers can choose corresponding security service providers to provide installation, maintenance and corresponding monitoring services before construction and operation. In this way, when the owner moves in, once there are any problems, the supplier responsible for safe operation can directly provide corresponding maintenance and solutions. And it is one-stop management and quality service. Many alarm monitoring service providers provide one-stop services from products to installation, maintenance and networking. Ensure safety while providing more convenience. Once there is a problem, customers don't need to deal with it themselves (for example, go to the equipment manufacturer, etc.). ), but by the service provider for comprehensive maintenance, save unnecessary trouble and contradiction. At the same time, it has a two-year warranty.