I don't think there is an English RMA available...

http://aquacomputer.de/rma-formular.html

Here is the translation:

"Ihr vollständiger Name" - your full name
"Straße + Hausnummer" - street, house number
"Adresszusatz" - additional address information, for example apartment number
"Postleitzahl" - zip code
"Ort" - City
"Ihre Mail Adresse" - email address
"Telefonnummer" - phone number, it is not mandatory to give that information
"Aqua Computer Kundennummer" - customer number from Aqua Computer, if you already have one
"Produktname" - name of the product, in your case: farbwerk
"Kaufdatum" - date of purchase
"Ausführliche Fehlerbeschreibung" - detailed description of the problem
"Zubehörliste" - accessory, it is recommended to send also the LED strips and the connector cables you used in
"Sicherheitsfrage" - add up the numbers

Or you can send them an email at support@aqua-computer.de
They will communicate with you in English.