I think the pop-up electronics box is the same/similar to mine on my 306 canyon.
Mine has a electric ram raising and lowering the whole box and i can remove a pin on top of the ram to disconnect it.
Be careful when disconnecting it as the whole box is heavy and may fall down and squeeze your finger/hand, do that in 2 people.
Then the whole box moves freely up and down, but you need a rope or similar to block the whole box it in the most open/up position to work under and behind.
Not sure where you can attach the rope on the 330Express, i have the rope going around the T-Top legs and be careful that rope does not slip and box flips down.
You will need to work blindly just using your fingers to feel where the screws are, i used my phone as mirror to find the cable plugs for the cables ii needed to attach.
Frequently i take videos or photos from such hidden spaces as this helps me to do stuff blindly.
My Garmins should have a bolt and a kind of treaded plate that fixes them on the panel, not sure how your devices are installed, you write of screws.
If screws then the task should be rather simple, use a short screwdriver, find the screw by feeling it and unscrew the screws if bolts and nuts then it becomes a bit more complicated.
Installer glued my electronics panel in place most likely using 5200 and that will be "fun" to remove the panel if i need to.
Do you have the old Furuno grey NavNet units and it developed screen delaminated?
If so, i had two probably 1999 original installed Furuno units with same problem, after hours of searching i found a company (in Florida i believe) who sell new screens but cost and shipping to Costa Rica was so high that i decided to replace it with something more modern and capable.
My system had also a open array radar and many electric boxes, adapters, cables inside the console so i freed a lot of space removing that.
Chris