Hey folks, looking for some advice because I don't know how to proceed.

This house came with vinyl siding and I noticed rot under it. The rot terminates up high behind where this soffit meets with the exterior wall. I need to get in here to figure out how water is getting in and then make necessary repairs, but the soffit is really in the way.

I've already removed the rot lower down - I had to remove vinyl siding, a layer of foam board, a layer of rotten OSB, the original rotten siding, and the original rotten sheathing. All of those layers are still present behind this soffit.

When I take the soffit vent off, there's a layer of OSB directly above it. Really don't know how to gain access here.

Any ideas?