Thank you both so much! An oscillating tool and a circular saw both seem affordable, and this project now seems very doable this weekend. Thank you thank you!

What is the best way to cut into a wood kitchen wall panel to enlarge an appliance cut out? We need to replace a non-functioning under the counter oven. Store will be doing the actual oven un/install, but we need to prep the spot so that they can essentially pull the old one out and slip the new one in.

I need an additional 1/2" height for the new cutout. The piece that needs to be cut is a plank of solid wood, probably 3/4" thick.

I'm hoping there is a method that doesn't involve totally uninstalling the old oven ourselves. It looks like there is a bit of a space between the top of the old oven and the bottom of the plank. Could I perhaps insert a tool to begin cutting from there? If I use a Japanese hand saw, what would be the best way to get the cut started?

And FWIW We don't have any heavy duty power tools, but don't mind investing in something we could use more than once, as folks who have occasional home repairs.

Thanks in advance for any insight.