Hi, Vadurr; When the engine "refused to start", do you mean that it cranks, but won't fire? I'm assuming so since you tested for spark. The window issue is a bit troubling. Have you checked the battery, itself, and all connections? Including various grounds going to the engine from the harness'?
Please describe how you checked for spark.
Please reply with the questions and we can go from there. Always start with the basics.
Loren