Ecumaster classic don't work

Hello

The ecumaster on my audi tt 8n doesn’t work anymore. It took my 6 months to repair my engine because of cooling problems. The ecu had no electricity due that 6 months. Now engine ready. But ecu doesn’t work anymore. When i plug in my laptop no dat shows up. Has anyone idea of the problem ?

Greetings Hein

first you have to test the ground cables and the 12v source…