After installing a new battery the car will not start?

Yep, you must register the battery when installing a new battery here is information on it.

There are two ways to carry out a voltage interruption of the 12-V battery:

Manually by disconnecting the battery ground lead

With the diagnostic system

1. Manually: Carry out the following steps:

Switch off and disconnect battery charger

Turn off ignition.

For vehicles with ignition key: Ignition key in neutral position

Vehicles with ID transmitter: Remove ID transmitter from slot

For vehicles with Comfort Access: Secure terminal 30

Disconnect negative battery lead

Reconnect battery ground lead (to ensure bus activity)

Observe a waiting period of 5-10 s

Disconnect negative battery lead

Observe a waiting period of approx. 1 minute

Connect battery ground lead

Connect and switch on battery charger

Switch on ignition

2. With the diagnostic system:

03 Body
Voltage supply
Activate rest state
Power-down command

Here is more information:

If the vehicle electrical system of electric vehicles is not accessible due to a faulty 12 V battery, proceed as follows:

Battery exchange in electrified vehicles

Vehicles with the automatic engine start-stop function or particular engine types and optional equipment are equipped with a special vehicle battery (AGM battery), since only this battery type can provide elevated power requirements over the extended service life. Installing a different vehicle battery can cause problems with vehicle electronics, can reduce functions or can cause leakage of battery acid.

Vehicles with energy management systems (IBS, power module): Register battery exchange.

The vehicle electrical system is informed about the vehicle battery characteristic data, such as type, size, age and current power capacity. Therefore, there will always be only one work scope provided that is permitted by the current status of information.

When installing a new vehicle battery, the battery must be registered and thus must also be registered with the vehicle electrical system.

Diagnosis system:

Register battery exchange.

Service functions

Body

Voltage supply

Register battery exchange

When retrofitting, a more powerful battery may be used. Standard batteries may always be replaced by AGM batteries with the same specifications.

When installing a battery of a different size or a different battery type, this change in vehicle data must be programmed into the vehicle data in accordance with specifications.

Check out the images (below). Please upload pictures or videos in your response of the problem so we can see what's going on.

Yep, it has been a minute. I hope all is well. So, it sounds like you had a voltage surge when you connected the battery which can happen, I would start by checking all fuses. here is a guide to help and I have included where the fuses are, please test them with the system on:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

If all of the fuses are okay let's do a CAN scan. You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Check out the images (below). Please upload pictures or videos in your response to the problem so we can see what's going on.

Yep, rats will do damage. I don't know what it is but they like to eat wiring. Some say it is the insolation tastes good to them. Thanks for letting us know, we are here to help, please use 2CarPros anytime. Nice talking with you again :) Kenny