1. Find the manual switch on the hydraulic manhole cover, usually located on the edge or bottom of the manhole cover. The manual switch is usually a round knob that can be manually rotated to open the hydraulic manhole cover.
2. The manual switch is locked and a key needs to be used to unlock the manual switch. The key is usually held by the operator or maintenance personnel. If you do not have the key, you need to contact the corresponding department or personnel to unlock it.
3. Rotate the manual switch to the position to open the hydraulic manhole cover. It usually requires hard rotation. After opening, the hydraulic manhole cover will automatically stop at a fixed position, allowing necessary repairs and maintenance.