Power and LED first
No LED on a battery camera: charge 30 minutes. A shaded solar panel will also drain over time.
A blinking LED means it is still in pairing, not online. Run the add-device guide again.
For indoor units check the outlet. For an NVR check the PoE port LEDs.
Then the network
A new router or password: pair bulb and desktop cameras again on 2.4 GHz. Dual-lens Wi-Fi cameras use Wi-Fi 4 or Wi-Fi 6.
On a 4G camera, confirm the SIM has data and is seated.
A phone VPN can hide a newly paired device in the app for a while.
Stale account rows
After a reset, the old row stays offline. Delete it and add the device again.
Do not keep the same unit on two accounts. Remove it from the first account before adding it to the second.