THe left bonet latch is direct connect to the handle insode. THe right latch is connected to the left latch. It is almsot always the right latch that gives issues first due to the piggy back cable coming undone or breaking. I have had lock with a long screwdriver from underneath on a couple rigs.
You could also try someone doing the lever while you push down (relieving the pressure a bit) on the stuck latch, also sometimes you can just get enough grip to move the bonnet around ever so slightly, again might just be enough to release it.
For me, it was my left latch. Having someone pull the latch while you lift will work, or vice versa. In the absence of a helper, you can put a broomstick, shower curtain rod, or some other long shaft and wedge it between the ground. This will pop the bonnet up as you pull the lever. I would imagine that this will work for either side.
When I had such issues, it was due to the male side of the left latch (on the bonnet) getting worked out of specified tightness or length. I had to take a screwdriver and tighten it. All has been well since.