My disabled son( can still have fun)

Hi my name is Daniel, and I have a son that had a blood clot in his brain at 28 days old which has left him with no motor skills he is 11 years old now. As a parent it was so hard to watch my son pretty much bed ridden. So I made him a power wheels that is remote controlled. It has changed his life,my daughter and I walk while controlling him around the block daily and he couldn't love this more the smile on his face is wonderful. But I need to upgrade things like controller, steering, motors,exc. Witch at the time is why I'm asking for help. I do have his car still up and running but would like to create the next one before something breaks. Thank you for even taking time to read this god bless.