please, anyone, send me some info-

driving home a socket fell on my battery positive terminal grounding to the chassis, arcing and starting a trunk fire

i purchased a new battery, cut the battery cable to a clean point and added a new connector.
rewired everything to my best ability,

CURRENT SYMPTOMS
key will turn all the way to start no problem,
dash comes on, i hear electronics turn on throughout the car
the aux battery has charge

when i turn the key to start literally NOTHING happens, no crank attempt, dash doesnt flicker, nothing.
when i press the brake i CANT shift from park. using the shift release and put into neutral, trying to start the car results in NOTHING again.

i really REALLY like my 320 & dont want to call it totaled. but i have no idea where else to go from here in diagnosis , so please help lol

 

test mercedez benz is quite pricey