@Lino Azzopardi, welcome here in this hive.
First of all, where are you located at, which country?
Then I do not believe firsthand in a dead ECU, only because a dealer, not a knowing person, tells me it might be like that.
Check or let somebody check your scoots rectifier/ regulator before you set further measures.
If your regulator is ok, check your generators tryfold plugs output.
Take out all fuses and look at their terminals.
There should not be any corrosion or green stuff nor should they be loose.
Look up all your cable harness under your seating area. There might be somewhere a blank cable touching ground and causes this symptoms.
Ask if something is unclear, here are many people who are willing to help.