Cant open hood?

Can you visually determine anything by visually looking through the opening with a flashlight? Is it possible that the linkage rod has come loose, or bent, and the solution lies in prodding it with a screwdriver or something to make up for what the lever can't do.

Not completely closed, is it completely latched and just resting on the battery charger? Is it on the safety latch, and loose. It would almost be a need for a visual, hands on approach to give you some guidance, since it is a special circumstance.

Some makes and models, you might be able to remove front grill and reach release mechanism. Depending on where the steel cable broke, you might be able to reach the steel cable, then use a pair of vice-grips on the cable itself and pull. Sometimes it helps when your pulling on cable to have a helper pop the hood with palm of the hand in area of release mechanism, to open. With it open, I usually lube the release mechanism. You can do what you think best about the cable. In the past, I have used a long piece of wire hanging down from release mechanism, I could reach the wire through the front grill to open the hood. Of course if you want to replace whole cable release assemble, that is fine, also.

There is no published service procedure for getting a hood open when the cable breaks. The only possible way is to look through the grill and see if you can determine where the cable attaches, or possibly reach up from below.