Key wount go in after batter was reconnected

surely not done with batter connected, right
or battery reconnected backwards.
clicks key off? no told when or how.
my wild wild guess, battery is dead or simply DIS charged.

Double check your connections to the battery and also the starter. Be careful at the starter with battery connected you don't want to touch any metal with your wrench while tightening the wires best to disconnect wires to battery then tighten starter positive then reconnect batter terminals.

put key in ignition turn to number 2 and press the fob buttons open close etc. see if that reset system. also if you charged the batter while on the vehicle you can only charge them with a tried and tested charger from mercedes as you can damage the engine management unit and the voltage control module fitted to the vehicle. failing that you will need to remove the negative lead on battery and leave off for an hour or so. and reconnect, the alarm will still go off until its internal battery goes flat ruf 30min or so. when reconnecting battery make sure the doors are all unlocked and boot is unlocked, you also will need the code for the radio and other units that can be in the vehicle from manufacture. if this does not work then you may need another unit to replace before the engine will start again as it has been damaged. when battery connected sit in the vehicle and turn ignition to number 2 and press fob to lock unlock doors then try to start engine if all goes well the engine and alam will not be a problem anymore

close all doors. Reconnect the battery. When alarm start sound - lock and unlock driver door with the key, not remote.

Perfectly, they will. All u need for now is to have the jammed key removed.

insert key turn to on position alarm should silence
once bat conected start truck

disconnect the ground cable only on the batter for two minutes, be sure the key is not in the ignition, reconnect cable, turn key to on, then turn off. remove the key, reinsert it and crank the car .

Pull the security relay, leave battery disconnected for about 20 mins. Insert relay and reconnect batter and try remote.

see as far concern as matter of fact most of the vehicle boot come's with either electrical or mechanical system operated so see for that if it is motor operated then if motor is jam then it wount open easily see for the key lock system if that too is jam it wount open up in this case take your car to the nearest authorised VW, SKODA, AUDI ..etc  dealer or service centre that will help out your car problem till then my friend have happy motoring see you soon

at this point you have 2 options, 1, go to a parts store and get a jimmy kit that helps you break into the car by unlocking the door, whicch sometimes can be tricky or if you have aaa they will unlock it for you for free, 2, you would have to reach from underneath and feel around for the cable, folow it to the latch assembaly and carefully release the latch assembaly, this way wil be very difficult and a tight area.
Good Luck.