Fail to reconnect to doorbell

Today my internet service was suspended for about 3 hours due to routine maintenance. After resetting my modem, my wifi restarts to work well with the same password. But all of my devices show offline. I tried to reconnect these devices to wifi, but initially, it didn't work. I have four battery-powered- stick-up cameras and one doorbell(2nd generation) with a chime. I read the website of Ring how to fix this issue: * If you have a device with a removable battery, remove the battery and wait 15 seconds before reinserting it. This will reboot the device, which may help to fix wifi connectivity issues. I followed this instruction and all of the Cameras with removable batteries now are working well. The chime also connects to wifi too. Unfortunately, my video doorbell(2nd generation) doesn't have a removable battery, therefore it still shows offline. Even if I tried to do all of the solutions: 1 recharge the battery, 2. restart my modem at least three times, 3.. reconnect to wifi over 10 times, still failed to connect to my wifi. I don't know how to fix it. Thus I am writing to ask for your help.