Help Merc S class 430 1999 Alarm problem

[DJ635]

hi Guys
Long story short ... replaced my battery and now the alarm is going off every time I connect the negative terminal
also have to manually open boot and door with metal key as the key fob is not working to open the locks or deal arm the car

is there a reset i need to do as I've been through this before where all the warning light turn on and then cleared them by the turning of the wheel trick seen on U-tube.

please help

[V12 AMG]

Firstly check your key.
Secondly check the alarm siren.

[DJ635]

key is fine batteries checked 100% ... btw the car seems to be in alarm mode as the dash back lights don't turn on

It is like its immobilised.
Key won't turn in ignition and doors don't unlock unless metal key used!?

alarm is sounding and indicators