| Hi
I had the same problem, electronic release would intermittenly stop working. I was forced to use the manual release (under rear seat base) for weeks and ultimately did same as you, stripped boot panel away and had a fiddle around, miraculously it worked again.....for about two days before packing in.
Mine wixed under warranty and had a complete rear boot grip/handle as was advised you cannot buy just the electronic switch on its own!!! Others may well correct me here but that's dealers for you, why repair when can completely replace.
Try a breakers yard or mini tuner who may have an old boot grip you can strip down, would be easier than getting new grip and having it painted to match car etc.
Hope that helps | 
