can i replace the bottom of a series 6 apple watch

I doubt it. Apple would probably just replace the whole watch.

For repair & service:

watch Repair - Official Apple Support

watch Service Pricing - Apple Support

Did the wire come out, when it was charging ? Had mine plugged up n charging, my grandson reached over to grab his cell, knocked mine off & back of watch was stuck on the charger still, that’s when I looked at bottom of my watch n saw a tiny wire come undone, now I am going to have to put n the shop n get wire soddered back on, can’t even charge with it like it is now, do you know which watch is the newest one out now?