I have the same problem with my key I was replacing the circuit board the new key case ( FROM EBAY ) well after installing all the parts inside including the transponder well wouldn't you know I DROPPED THE KEY !!!.. It popped open these from ebay are not good at sealing with out glue it together and use an epoxy because contact cement does not work it pops open !!! It fell into 10 pieces and I cannot find the transponder . It fell on a black drive way and I have swept , vacuumed searched and searched until my eyes are sore in this super hot weather sweating my behind off . I was so frustrated . Everywhere I have looked on line for a new key is so expensive $485 to almost $700. Needs wings says they raised the price back in October 2018 and Mercedes is discontinuing these very soon . So the Crossfire is going to be a car that will not be saved due to the expense of repairing it as some have said the key is worth more than the car. I wish I could find a way to fix this cheaply but guess this is not possible unless some computer wiz can come up with a cheap fix . I only have one working remote now . The one with out transponder just starts the engine only to fizzle out. Guess having to tear my good remote apart to get the transponder out to glue to the ignition ring is my only option is very scary now I lost the first transponder . If I could find a used remote and take the one with working remote tucked behind the dash . I have been looking into most all these post with no luck other than spend almost $700 for a new key worth more than the car . I just bought this car and now thinking of perhaps letting it go due to severe repair costs . I own a 2013 Mustang and bought aftermarket flip keys like the crossfire and I programed it easily found it on youtube how to do. it works great . Now these Crossfires are old and the security is way past the cars worth. Perhaps as people get tired of trying to fix these and they end up junked due to repair issues with Make those with pristine cars make them worth more but still a pristine cars can fail as well as those with driver cars used on weekend with high miles. I loved this car but !!! not sure what to do . thanks for any help with possible easy fixes or possible removing skreem all together . Thanks