XC70: Electrical 2013 xc70 chaos after battery replacement

[tonys1966]

hi folks-decided to carry out a battery replacement as preventive maintainance-ahem really wish i hadnt....

changed battery for a bosch newbie-started car,reset windows which were about the only codes to come up on first scan
Took out for a drive-instant limp mode,loads dash warnings and an armful of codes,coo codes[too many to mention,comms,algorithms etc]-so i cleared these and they keep coming back
battery showing 12.4 v engine stopped 14.4 running[vida]

its not a stop start so i didnt code battery in[if you can]

any idea what has went wrong-loads strange things happen=idles at 1500 rpm,sometimes wont come out of p,tells you its not in p when it is

also any idea what the wire is that goes from positive to negative terminal-its got a thin bit to blow in case of an accident or major short i should think-looks like it has been pinched in middle a bit-could this be relevant

previous owner had issues with the car,but i havent,although there were a raft of faults logged when i bought vida they all cleared off and didnt return[except my faulty pam module]

as usual any help welcome-it must have happened tosomebody else on here before lol