B&D Cordless Self-Propelled Lawn Mower SPCM1936

We have had this lawn mower for a number of years and it has been ideal for us. It now will not start. It looks like the orange 'key' and the part on the lawn mower where you inset it are askew. I bought a new key on Amazon, but it won't fit into slots. I took it to the only B&D authorized repair place about 3 weeks ago and every time I call, they tell me to be patient. I've tried to find out the part item number to see if I could replace it myself, but it is difficult to tell. The B&D customer service rep believes it is a 'cordset', but I can find no info on how to replace that. Surprisingly, not finding anything on YouTube. Can you #1 tell me if you believe it is the cordset, and #2 tell me where I would find instructions to replace it? Thanks very much!