hello i am having a serious issue with my defender and it is currently stranded by the beach

my 1998 defender started cranking over while i was driving it so i tried to shut it off and pulled the key out and it was still cranking over i tried to undo the battery and when i touched the positive terminal it was extremly hot and i burned my finger but managed to get it off

i tried removing the starter relay under the center of the dash and re hooking up the battery but it was still trying to crank over, so i am assuming it is a problem with either the solenoid or the hot wire from the battery to the starter

any and all help is greatly appreciated thank you