You are right in this is a hybrid catt. I'm thinking it looks like an Slc. (Sophronitis x Laelia x Cattleya).
Your plant suffers from dehydration caused by root loss. In addition to following correct watering procedures and repotting (which you did), I would keep the plant in lower light (an East window, maybe?) and keep the humidity really high (70-80%) while the plant is recovering. A hot South window is too much for most SLCs (as evidenced by burn in your photo). When it plumps up, you can keep it in your South window, but do add some shading...a sheer curtain, another larger plant, etc.