It is the type with "dummy battery" that goes into the battery slot next to the SD card. I'll have to play with it a little when I get home tonight to see if pressure affects anything, but I doubt it. The camera works fine when I boot up normally into regular Canon mode, it's only when I try and boot into CHDK (through either the SD card lock or by starting the camera in play mode) that I get the "no memory card" error. If it was pressure it seems to me that it would either always not work, or randomly not work depending on how the plug was applying pressure... Though unfortunately I don't have any better ideas, so you could be right.